diff --git a/src/Symfony/Component/Notifier/Bridge/Infobip/Tests/InfobipTransportFactoryTest.php b/src/Symfony/Component/Notifier/Bridge/Infobip/Tests/InfobipTransportFactoryTest.php
index 2d3ab0804d..1478ebb169 100644
--- a/src/Symfony/Component/Notifier/Bridge/Infobip/Tests/InfobipTransportFactoryTest.php
+++ b/src/Symfony/Component/Notifier/Bridge/Infobip/Tests/InfobipTransportFactoryTest.php
@@ -19,7 +19,7 @@ use Symfony\Component\Notifier\Transport\Dsn;
 
 final class InfobipTransportFactoryTest extends TestCase
 {
-    public function testCreateWithDsn(): void
+    public function testCreateWithDsn()
     {
         $factory = new InfobipTransportFactory();
 
@@ -30,7 +30,7 @@ final class InfobipTransportFactoryTest extends TestCase
         $this->assertSame('infobip://host.test?from=0611223344', (string) $transport);
     }
 
-    public function testCreateWithNoFromThrowsMalformed(): void
+    public function testCreateWithNoFromThrowsMalformed()
     {
         $factory = new InfobipTransportFactory();
 
@@ -40,7 +40,7 @@ final class InfobipTransportFactoryTest extends TestCase
         $factory->create(Dsn::fromString($dsnIncomplete));
     }
 
-    public function testSupportsInfobipScheme(): void
+    public function testSupportsInfobipScheme()
     {
         $factory = new InfobipTransportFactory();
 
@@ -51,7 +51,7 @@ final class InfobipTransportFactoryTest extends TestCase
         $this->assertFalse($factory->supports(Dsn::fromString($dsnUnsupported)));
     }
 
-    public function testNonInfobipSchemeThrows(): void
+    public function testNonInfobipSchemeThrows()
     {
         $factory = new InfobipTransportFactory();
 
diff --git a/src/Symfony/Component/Notifier/Bridge/Infobip/Tests/InfobipTransportTest.php b/src/Symfony/Component/Notifier/Bridge/Infobip/Tests/InfobipTransportTest.php
index 767f63d4ba..ce616021ca 100644
--- a/src/Symfony/Component/Notifier/Bridge/Infobip/Tests/InfobipTransportTest.php
+++ b/src/Symfony/Component/Notifier/Bridge/Infobip/Tests/InfobipTransportTest.php
@@ -20,14 +20,14 @@ use Symfony\Contracts\HttpClient\HttpClientInterface;
 
 final class InfobipTransportTest extends TestCase
 {
-    public function testToStringContainsProperties(): void
+    public function testToStringContainsProperties()
     {
         $transport = $this->getTransport();
 
         $this->assertSame('infobip://host.test?from=0611223344', (string) $transport);
     }
 
-    public function testSupportsMessageInterface(): void
+    public function testSupportsMessageInterface()
     {
         $transport = $this->getTransport();
 
@@ -35,7 +35,7 @@ final class InfobipTransportTest extends TestCase
         $this->assertFalse($transport->supports($this->createMock(MessageInterface::class)));
     }
 
-    public function testSendNonSmsMessageThrowsException(): void
+    public function testSendNonSmsMessageThrowsException()
     {
         $transport = $this->getTransport();
 
diff --git a/src/Symfony/Component/Notifier/Bridge/LinkedIn/Tests/LinkedInTransportFactoryTest.php b/src/Symfony/Component/Notifier/Bridge/LinkedIn/Tests/LinkedInTransportFactoryTest.php
index 54373c7c90..c4943464a3 100644
--- a/src/Symfony/Component/Notifier/Bridge/LinkedIn/Tests/LinkedInTransportFactoryTest.php
+++ b/src/Symfony/Component/Notifier/Bridge/LinkedIn/Tests/LinkedInTransportFactoryTest.php
@@ -10,7 +10,7 @@ use Symfony\Component\Notifier\Transport\Dsn;
 
 final class LinkedInTransportFactoryTest extends TestCase
 {
-    public function testCreateWithDsn(): void
+    public function testCreateWithDsn()
     {
         $factory = new LinkedInTransportFactory();
 
@@ -21,7 +21,7 @@ final class LinkedInTransportFactoryTest extends TestCase
         $this->assertSame('linkedin://testHost', (string) $transport);
     }
 
-    public function testSupportsLinkedinScheme(): void
+    public function testSupportsLinkedinScheme()
     {
         $factory = new LinkedInTransportFactory();
 
@@ -29,7 +29,7 @@ final class LinkedInTransportFactoryTest extends TestCase
         $this->assertFalse($factory->supports(Dsn::fromString('somethingElse://host/path')));
     }
 
-    public function testNonLinkedinSchemeThrows(): void
+    public function testNonLinkedinSchemeThrows()
     {
         $factory = new LinkedInTransportFactory();
 
@@ -39,7 +39,7 @@ final class LinkedInTransportFactoryTest extends TestCase
         $factory->create(Dsn::fromString($dsn));
     }
 
-    public function testIncompleteDsnMissingUserThrows(): void
+    public function testIncompleteDsnMissingUserThrows()
     {
         $factory = new LinkedInTransportFactory();
 
diff --git a/src/Symfony/Component/Notifier/Bridge/LinkedIn/Tests/LinkedInTransportTest.php b/src/Symfony/Component/Notifier/Bridge/LinkedIn/Tests/LinkedInTransportTest.php
index 4f0bdc058a..148043e948 100644
--- a/src/Symfony/Component/Notifier/Bridge/LinkedIn/Tests/LinkedInTransportTest.php
+++ b/src/Symfony/Component/Notifier/Bridge/LinkedIn/Tests/LinkedInTransportTest.php
@@ -17,12 +17,12 @@ use Symfony\Contracts\HttpClient\ResponseInterface;
 
 final class LinkedInTransportTest extends TestCase
 {
-    public function testToString(): void
+    public function testToString()
     {
         $this->assertSame(sprintf('linkedin://host.test'), (string) $this->getTransport());
     }
 
-    public function testSupportsChatMessage(): void
+    public function testSupportsChatMessage()
     {
         $transport = $this->getTransport();
 
@@ -30,7 +30,7 @@ final class LinkedInTransportTest extends TestCase
         $this->assertFalse($transport->supports($this->createMock(MessageInterface::class)));
     }
 
-    public function testSendNonChatMessageThrows(): void
+    public function testSendNonChatMessageThrows()
     {
         $transport = $this->getTransport();
 
@@ -39,7 +39,7 @@ final class LinkedInTransportTest extends TestCase
         $transport->send($this->createMock(MessageInterface::class));
     }
 
-    public function testSendWithEmptyArrayResponseThrows(): void
+    public function testSendWithEmptyArrayResponseThrows()
     {
         $this->expectException(TransportException::class);
 
@@ -60,7 +60,7 @@ final class LinkedInTransportTest extends TestCase
         $transport->send(new ChatMessage('testMessage'));
     }
 
-    public function testSendWithErrorResponseThrows(): void
+    public function testSendWithErrorResponseThrows()
     {
         $this->expectException(TransportException::class);
         $this->expectExceptionMessage('testErrorCode');
@@ -83,7 +83,7 @@ final class LinkedInTransportTest extends TestCase
         $transport->send(new ChatMessage('testMessage'));
     }
 
-    public function testSendWithOptions(): void
+    public function testSendWithOptions()
     {
         $message = 'testMessage';
 
@@ -127,7 +127,7 @@ final class LinkedInTransportTest extends TestCase
         $transport->send(new ChatMessage($message));
     }
 
-    public function testSendWithNotification(): void
+    public function testSendWithNotification()
     {
         $message = 'testMessage';
 
@@ -175,7 +175,7 @@ final class LinkedInTransportTest extends TestCase
         $transport->send($chatMessage);
     }
 
-    public function testSendWithInvalidOptions(): void
+    public function testSendWithInvalidOptions()
     {
         $this->expectException(LogicException::class);
 
diff --git a/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackActionsBlockTest.php b/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackActionsBlockTest.php
index fba5ccf7c5..2a21a39133 100644
--- a/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackActionsBlockTest.php
+++ b/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackActionsBlockTest.php
@@ -16,7 +16,7 @@ use Symfony\Component\Notifier\Bridge\Slack\Block\SlackActionsBlock;
 
 final class SlackActionsBlockTest extends TestCase
 {
-    public function testCanBeInstantiated(): void
+    public function testCanBeInstantiated()
     {
         $actions = new SlackActionsBlock();
         $actions->button('first button text', 'https://example.org')
@@ -47,7 +47,7 @@ final class SlackActionsBlockTest extends TestCase
         ], $actions->toArray());
     }
 
-    public function testThrowsWhenFieldsLimitReached(): void
+    public function testThrowsWhenFieldsLimitReached()
     {
         $section = new SlackActionsBlock();
         for ($i = 0; $i < 25; ++$i) {
diff --git a/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackContextBlockTest.php b/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackContextBlockTest.php
index 2df45a4907..ebdced0a41 100644
--- a/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackContextBlockTest.php
+++ b/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackContextBlockTest.php
@@ -16,7 +16,7 @@ use Symfony\Component\Notifier\Bridge\Slack\Block\SlackContextBlock;
 
 final class SlackContextBlockTest extends TestCase
 {
-    public function testCanBeInstantiated(): void
+    public function testCanBeInstantiated()
     {
         $context = new SlackContextBlock();
         $context->text('context text without emoji', false, false);
@@ -47,7 +47,7 @@ final class SlackContextBlockTest extends TestCase
         ], $context->toArray());
     }
 
-    public function testThrowsWhenElementsLimitReached(): void
+    public function testThrowsWhenElementsLimitReached()
     {
         $context = new SlackContextBlock();
         for ($i = 0; $i < 10; ++$i) {
diff --git a/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackHeaderBlockTest.php b/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackHeaderBlockTest.php
index c899b1822c..00d916c933 100644
--- a/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackHeaderBlockTest.php
+++ b/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackHeaderBlockTest.php
@@ -17,7 +17,7 @@ use Symfony\Component\Notifier\Exception\LogicException;
 
 final class SlackHeaderBlockTest extends TestCase
 {
-    public function testCanBeInstantiated(): void
+    public function testCanBeInstantiated()
     {
         $header = new SlackHeaderBlock('header text');
         $header->id('header_id');
@@ -32,7 +32,7 @@ final class SlackHeaderBlockTest extends TestCase
         ], $header->toArray());
     }
 
-    public function testThrowsWhenTextExceedsCharacterLimit(): void
+    public function testThrowsWhenTextExceedsCharacterLimit()
     {
         $this->expectException(LogicException::class);
         $this->expectExceptionMessage('Maximum length for the text is 150 characters.');
@@ -40,7 +40,7 @@ final class SlackHeaderBlockTest extends TestCase
         new SlackHeaderBlock(str_repeat('h', 151));
     }
 
-    public function testThrowsWhenBlockIdExceedsCharacterLimit(): void
+    public function testThrowsWhenBlockIdExceedsCharacterLimit()
     {
         $this->expectException(LogicException::class);
         $this->expectExceptionMessage('Maximum length for the block id is 255 characters.');
diff --git a/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackSectionBlockTest.php b/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackSectionBlockTest.php
index 7e1e98981d..0a1c097bcf 100644
--- a/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackSectionBlockTest.php
+++ b/src/Symfony/Component/Notifier/Bridge/Slack/Tests/Block/SlackSectionBlockTest.php
@@ -17,7 +17,7 @@ use Symfony\Component\Notifier\Bridge\Slack\Block\SlackSectionBlock;
 
 final class SlackSectionBlockTest extends TestCase
 {
-    public function testCanBeInstantiated(): void
+    public function testCanBeInstantiated()
     {
         $section = new SlackSectionBlock();
         $section->text('section text');
@@ -44,7 +44,7 @@ final class SlackSectionBlockTest extends TestCase
         ], $section->toArray());
     }
 
-    public function testThrowsWhenFieldsLimitReached(): void
+    public function testThrowsWhenFieldsLimitReached()
     {
         $section = new SlackSectionBlock();
         for ($i = 0; $i < 10; ++$i) {
diff --git a/src/Symfony/Component/VarDumper/Dumper/HtmlDumper.php b/src/Symfony/Component/VarDumper/Dumper/HtmlDumper.php
index 0c2108eda2..a741481cf2 100644
--- a/src/Symfony/Component/VarDumper/Dumper/HtmlDumper.php
+++ b/src/Symfony/Component/VarDumper/Dumper/HtmlDumper.php
@@ -171,6 +171,9 @@ var refStyle = doc.createElement('style'),
         e.addEventListener(n, cb, false);
     };
 
+refStyle.innerHTML = 'pre.sf-dump .sf-dump-compact, .sf-dump-str-collapse .sf-dump-str-collapse, .sf-dump-str-expand .sf-dump-str-expand { display: none; }';
+(doc.documentElement.firstElementChild || doc.documentElement.children[0]).appendChild(refStyle);
+refStyle = doc.createElement('style');
 (doc.documentElement.firstElementChild || doc.documentElement.children[0]).appendChild(refStyle);
 
 if (!doc.addEventListener) {
@@ -665,9 +668,6 @@ pre.sf-dump:after {
 pre.sf-dump span {
     display: inline;
 }
-pre.sf-dump .sf-dump-compact {
-    display: none;
-}
 pre.sf-dump a {
     text-decoration: none;
     cursor: pointer;
@@ -699,12 +699,6 @@ pre.sf-dump code {
     padding:0;
     background:none;
 }
-.sf-dump-str-collapse .sf-dump-str-collapse {
-    display: none;
-}
-.sf-dump-str-expand .sf-dump-str-expand {
-    display: none;
-}
 .sf-dump-public.sf-dump-highlight,
 .sf-dump-protected.sf-dump-highlight,
 .sf-dump-private.sf-dump-highlight,