minor #17086 CS: use nowdoc instead of heredoc (gharlan)

This PR was merged into the 2.3 branch.

Discussion
----------

CS: use nowdoc instead of heredoc

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | —
| License       | MIT
| Doc PR        | —

if this is accepted, we could add the fixer to symfony level of php-cs-fixer: PHP-CS-Fixer/PHP-CS-Fixer#1580

Commits
-------

3dca549 use nowdoc instead of heredoc

Author: nicolas-grekas

Tests/DumperTest.php

@@ -54,7 +54,7 @@ public function testSetIndentation()
     {
         $this->dumper->setIndentation(7);
 
-        $expected = <<<EOF
+        $expected = <<<'EOF'
 '': bar
 foo: '#bar'
 'foo''bar': {  }
@@ -104,13 +104,13 @@ public function testSpecifications()
 
     public function testInlineLevel()
     {
-        $expected = <<<EOF
+        $expected = <<<'EOF'
 { '': bar, foo: '#bar', 'foo''bar': {  }, bar: [1, foo], foobar: { foo: bar, bar: [1, foo], foobar: { foo: bar, bar: [1, foo] } } }
 EOF;
         $this->assertEquals($expected, $this->dumper->dump($this->array, -10), '->dump() takes an inline level argument');
         $this->assertEquals($expected, $this->dumper->dump($this->array, 0), '->dump() takes an inline level argument');
 
-        $expected = <<<EOF
+        $expected = <<<'EOF'
 '': bar
 foo: '#bar'
 'foo''bar': {  }
@@ -120,7 +120,7 @@ public function testInlineLevel()
 EOF;
         $this->assertEquals($expected, $this->dumper->dump($this->array, 1), '->dump() takes an inline level argument');
 
-        $expected = <<<EOF
+        $expected = <<<'EOF'
 '': bar
 foo: '#bar'
 'foo''bar': {  }
@@ -135,7 +135,7 @@ public function testInlineLevel()
 EOF;
         $this->assertEquals($expected, $this->dumper->dump($this->array, 2), '->dump() takes an inline level argument');
 
-        $expected = <<<EOF
+        $expected = <<<'EOF'
 '': bar
 foo: '#bar'
 'foo''bar': {  }
@@ -154,7 +154,7 @@ public function testInlineLevel()
 EOF;
         $this->assertEquals($expected, $this->dumper->dump($this->array, 3), '->dump() takes an inline level argument');
 
-        $expected = <<<EOF
+        $expected = <<<'EOF'
 '': bar
 foo: '#bar'
 'foo''bar': {  }

Tests/ParserTest.php

@@ -90,7 +90,7 @@ public function testTabsInYaml()
 
     public function testEndOfTheDocumentMarker()
     {
-        $yaml = <<<EOF
+        $yaml = <<<'EOF'
 --- %YAML:1.0
 foo
 ...
@@ -473,7 +473,7 @@ public function testNonUtf8Exception()
      */
     public function testUnindentedCollectionException()
     {
-        $yaml = <<<EOF
+        $yaml = <<<'EOF'
 
 collection:
 -item1
@@ -490,7 +490,7 @@ public function testUnindentedCollectionException()
      */
     public function testShortcutKeyUnindentedCollectionException()
     {
-        $yaml = <<<EOF
+        $yaml = <<<'EOF'
 
 collection:
 -  key: foo
@@ -507,7 +507,7 @@ public function testShortcutKeyUnindentedCollectionException()
      */
     public function testMultipleDocumentsNotSupportedException()
     {
-        Yaml::parse(<<<EOL
+        Yaml::parse(<<<'EOL'
 # Ranking of 1998 home runs
 ---
 - Mark McGwire
@@ -527,7 +527,7 @@ public function testMultipleDocumentsNotSupportedException()
      */
     public function testSequenceInAMapping()
     {
-        Yaml::parse(<<<EOF
+        Yaml::parse(<<<'EOF'
 yaml:
   hash: me
   - array stuff
@@ -540,7 +540,7 @@ public function testSequenceInAMapping()
      */
     public function testMappingInASequence()
     {
-        Yaml::parse(<<<EOF
+        Yaml::parse(<<<'EOF'
 yaml:
   - array stuff
   hash: me
@@ -550,7 +550,7 @@ public function testMappingInASequence()
 
     public function testEmptyValue()
     {
-        $input = <<<EOF
+        $input = <<<'EOF'
 hash:
 EOF;
 
@@ -568,7 +568,7 @@ public function testCommentAtTheRootIndent()
                     'class' => 'Bar',
                 ),
             ),
-        ), Yaml::parse(<<<EOF
+        ), Yaml::parse(<<<'EOF'
 # comment 1
 services:
 # comment 2
@@ -585,7 +585,7 @@ class: Bar
 
     public function testStringBlockWithComments()
     {
-        $this->assertEquals(array('content' => <<<EOT
+        $this->assertEquals(array('content' => <<<'EOT'
 # comment 1
 header
 
@@ -596,7 +596,7 @@ public function testStringBlockWithComments()
 
 footer # comment3
 EOT
-        ), Yaml::parse(<<<EOF
+        ), Yaml::parse(<<<'EOF'
 content: |
     # comment 1
     header
@@ -613,7 +613,7 @@ public function testStringBlockWithComments()
 
     public function testFoldedStringBlockWithComments()
     {
-        $this->assertEquals(array(array('content' => <<<EOT
+        $this->assertEquals(array(array('content' => <<<'EOT'
 # comment 1
 header
 
@@ -624,7 +624,7 @@ public function testFoldedStringBlockWithComments()
 
 footer # comment3
 EOT
-        )), Yaml::parse(<<<EOF
+        )), Yaml::parse(<<<'EOF'
 -
     content: |
         # comment 1
@@ -644,7 +644,7 @@ public function testNestedFoldedStringBlockWithComments()
     {
         $this->assertEquals(array(array(
             'title' => 'some title',
-            'content' => <<<EOT
+            'content' => <<<'EOT'
 # comment 1
 header
 
@@ -655,7 +655,7 @@ public function testNestedFoldedStringBlockWithComments()
 
 footer # comment3
 EOT
-        )), Yaml::parse(<<<EOF
+        )), Yaml::parse(<<<'EOF'
 -
     title: some title
     content: |
@@ -684,7 +684,7 @@ public function testReferenceResolvingInInlineStrings()
             'map' => array('key' => 'var-value'),
             'list_in_map' => array('key' => array('var-value')),
             'map_in_map' => array('foo' => array('bar' => 'var-value')),
-        ), Yaml::parse(<<<EOF
+        ), Yaml::parse(<<<'EOF'
 var:  &var var-value
 scalar: *var
 list: [ *var ]
@@ -700,7 +700,7 @@ public function testReferenceResolvingInInlineStrings()
 
     public function testYamlDirective()
     {
-        $yaml = <<<EOF
+        $yaml = <<<'EOF'
 %YAML 1.2
 ---
 foo: 1
@@ -711,7 +711,7 @@ public function testYamlDirective()
 
     public function testFloatKeys()
     {
-        $yaml = <<<EOF
+        $yaml = <<<'EOF'
 foo:
     1.2: "bar"
     1.3: "baz"
@@ -737,7 +737,7 @@ public function testCommentLikeStringsAreNotStrippedInBlockScalars($yaml, $expec
 
     public function getCommentLikeStringInScalarBlockData()
     {
-        $yaml1 = <<<EOT
+        $yaml1 = <<<'EOT'
 pages:
     -
         title: some title
@@ -756,7 +756,7 @@ public function getCommentLikeStringInScalarBlockData()
             'pages' => array(
                 array(
                     'title' => 'some title',
-                    'content' => <<<EOT
+                    'content' => <<<'EOT'
 # comment 1
 header
 
@@ -772,7 +772,7 @@ public function getCommentLikeStringInScalarBlockData()
             ),
         );
 
-        $yaml2 = <<<EOT
+        $yaml2 = <<<'EOT'
 test: |
     foo
     # bar
@@ -788,7 +788,7 @@ public function getCommentLikeStringInScalarBlockData()
         baz
 EOT;
         $expected2 = array(
-            'test' => <<<EOT
+            'test' => <<<'EOT'
 foo
 # bar
 baz
@@ -797,15 +797,15 @@ public function getCommentLikeStringInScalarBlockData()
             ,
             'collection' => array(
                 array(
-                    'one' => <<<EOT
+                    'one' => <<<'EOT'
 foo
 # bar
 baz
 EOT
                     ,
                 ),
                 array(
-                    'two' => <<<EOT
+                    'two' => <<<'EOT'
 foo
 # bar
 baz