Introduce printers for Node and Position for ease of developing GTest test files

Source/core/core.gypi

 {
     'includes': [
         'core_generated.gypi',
     ],
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/KeyframeEffect.idl',
             'animation/EffectModel.idl',
             'animation/AnimationEffectReadOnly.idl',
@@ skipping 3700 matching lines @@
             '<(blink_core_output_dir)/testing/InternalDictionary.cpp',
             '<(blink_core_output_dir)/testing/InternalDictionary.h',
             '<(blink_core_output_dir)/testing/InternalDictionaryDerived.cpp',
             '<(blink_core_output_dir)/testing/InternalDictionaryDerived.h',
             '<(blink_core_output_dir)/testing/PluginPlaceholderOptions.cpp',
             '<(blink_core_output_dir)/testing/PluginPlaceholderOptions.h',
         ],
         'webcore_testing_files': [
             '<(blink_core_output_dir)/testing/InternalSettingsGenerated.cpp',
             '<(blink_core_output_dir)/testing/InternalSettingsGenerated.h',
+            'testing/CoreTestHelpers.cpp',
+            'testing/CoreTestHelpers.h',
             'testing/DictionaryTest.cpp',
             'testing/DictionaryTest.h',
             'testing/DummyPageHolder.cpp',
             'testing/DummyPageHolder.h',
             'testing/GCObservation.cpp',
             'testing/GCObservation.h',
             'testing/GarbageCollectedScriptWrappable.cpp',
             'testing/GarbageCollectedScriptWrappable.h',
             'testing/InternalSettings.cpp',
             'testing/InternalSettings.h',
@@ skipping 163 matching lines @@
             'style/ComputedStyleTest.cpp',
             'style/OutlineValueTest.cpp',
             'style/SVGComputedStyleTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }