bug #17568 Improved Bootstrap form theme for hidden fields (javiereguiluz)

This PR was squashed before being merged into the 2.7 branch (closes #17568).

Discussion
----------

Improved Bootstrap form theme for hidden fields

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #16925
| License       | MIT
| Doc PR        | -

Commits
-------

ba5d7f9 Improved Bootstrap form theme for hidden fields

Author: fabpot

Tests/AbstractBootstrap3LayoutTest.php

@@ -684,7 +684,7 @@ public function testSingleChoiceExpanded()
                         ./input[@type="radio"][@name="name"][@id="name_1"][@value="&b"][not(@checked)]
                     ]
             ]
-        /following-sibling::input[@type="hidden"][@id="name__token"][@class="form-control"]
+        /following-sibling::input[@type="hidden"][@id="name__token"]
     ]
 '
         );
@@ -844,7 +844,7 @@ public function testSingleChoiceExpandedWithoutTranslation()
                         ./input[@type="radio"][@name="name"][@id="name_1"][@value="&b"][not(@checked)]
                     ]
             ]
-        /following-sibling::input[@type="hidden"][@id="name__token"][@class="form-control"]
+        /following-sibling::input[@type="hidden"][@id="name__token"]
     ]
 '
         );
@@ -883,7 +883,7 @@ public function testSingleChoiceExpandedAttributes()
                         ./input[@type="radio"][@name="name"][@id="name_1"][@value="&b"][not(@checked)]'.$classPart.'
                     ]
             ]
-        /following-sibling::input[@type="hidden"][@id="name__token"][@class="form-control"]
+        /following-sibling::input[@type="hidden"][@id="name__token"]
     ]
 '
         );
@@ -930,7 +930,7 @@ public function testSingleChoiceExpandedWithPlaceholder()
                         ./input[@type="radio"][@name="name"][@id="name_1"][not(@checked)]
                     ]
             ]
-        /following-sibling::input[@type="hidden"][@id="name__token"][@class="form-control"]
+        /following-sibling::input[@type="hidden"][@id="name__token"]
     ]
 '
         );
@@ -966,7 +966,7 @@ public function testSingleChoiceExpandedWithBooleanValue()
                         ./input[@type="radio"][@name="name"][@id="name_1"][not(@checked)]
                     ]
             ]
-        /following-sibling::input[@type="hidden"][@id="name__token"][@class="form-control"]
+        /following-sibling::input[@type="hidden"][@id="name__token"]
     ]
 '
         );
@@ -1012,7 +1012,7 @@ public function testMultipleChoiceExpanded()
                         ./input[@type="checkbox"][@name="name[]"][@id="name_2"][@checked][not(@required)]
                     ]
             ]
-        /following-sibling::input[@type="hidden"][@id="name__token"][@class="form-control"]
+        /following-sibling::input[@type="hidden"][@id="name__token"]
     ]
 '
         );
@@ -1182,7 +1182,7 @@ public function testMultipleChoiceExpandedWithoutTranslation()
                         ./input[@type="checkbox"][@name="name[]"][@id="name_2"][@checked][not(@required)]
                     ]
             ]
-        /following-sibling::input[@type="hidden"][@id="name__token"][@class="form-control"]
+        /following-sibling::input[@type="hidden"][@id="name__token"]
     ]
 '
         );
@@ -1231,7 +1231,7 @@ public function testMultipleChoiceExpandedAttributes()
                         ./input[@type="checkbox"][@name="name[]"][@id="name_2"][@checked][not(@required)]
                     ]
             ]
-        /following-sibling::input[@type="hidden"][@id="name__token"][@class="form-control"]
+        /following-sibling::input[@type="hidden"][@id="name__token"]
     ]
 '
         );
@@ -1733,7 +1733,7 @@ public function testHidden()
 '/input
     [@type="hidden"]
     [@name="name"]
-    [@class="my&class form-control"]
+    [@class="my&class"]
     [@value="foo&bar"]
 '
         );