Remove internals.setEnableMockPagePopup().

Source/core/core.gypi

 {
     'includes': [
         'core_generated.gypi',
     ],
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/Animation.idl',
             'animation/AnimationEffect.idl',
             'animation/AnimationNode.idl',
@@ skipping 3452 matching lines @@
             'testing/GCObservation.h',
             'testing/GarbageCollectedScriptWrappable.cpp',
             'testing/GarbageCollectedScriptWrappable.h',
             'testing/InternalSettings.cpp',
             'testing/InternalSettings.h',
             'testing/Internals.cpp',
             'testing/Internals.h',
             'testing/LayerRect.h',
             'testing/LayerRectList.cpp',
             'testing/LayerRectList.h',
-            'testing/MockPagePopupDriver.cpp',
-            'testing/MockPagePopupDriver.h',
             'testing/NullExecutionContext.cpp',
             'testing/NullExecutionContext.h',
             'testing/PartialPrivateScriptTest.h',
             'testing/PrivateScriptTest.cpp',
             'testing/PrivateScriptTest.h',
             'testing/RefCountedScriptWrappable.cpp',
             'testing/RefCountedScriptWrappable.h',
             'testing/TypeConversions.h',
             'testing/URLTestHelpers.cpp',
             'testing/URLTestHelpers.h',
@@ skipping 110 matching lines @@
             'rendering/style/OutlineValueTest.cpp',
             'rendering/style/RenderStyleTest.cpp',
             'streams/ReadableStreamTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }