Separate the generated files from core and modules to their own sub-dirs.

Source/core/core.gypi

 {
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/Animation.idl',
             'animation/AnimationEffect.idl',
             'animation/AnimationPlayer.idl',
             'animation/AnimationNode.idl',
             'animation/AnimationTimeline.idl',
             'animation/Timing.idl',
@@ skipping 3279 matching lines @@
           'testing/GCObservation.idl',
           'testing/InternalProfilers.idl',
           'testing/InternalSettings.idl',
           'testing/Internals.idl',
           'testing/LayerRect.idl',
           'testing/LayerRectList.idl',
           'testing/MallocStatistics.idl',
           'testing/TypeConversions.idl',
         ],
         'generated_webcore_testing_idl_files': [
-          '<(SHARED_INTERMEDIATE_DIR)/blink/InternalRuntimeFlags.idl',
-          '<(SHARED_INTERMEDIATE_DIR)/blink/InternalSettingsGenerated.idl',
+          '<(core_output_dir)/InternalRuntimeFlags.idl',
+          '<(core_output_dir)/InternalSettingsGenerated.idl',
         ],
         'webcore_testing_files': [
-            '<(SHARED_INTERMEDIATE_DIR)/blink/InternalSettingsGenerated.cpp',
-            '<(SHARED_INTERMEDIATE_DIR)/blink/InternalSettingsGenerated.h',
+            '<(core_output_dir)/InternalSettingsGenerated.cpp',
+            '<(core_output_dir)/InternalSettingsGenerated.h',
             'testing/DummyPageHolder.cpp',
             'testing/DummyPageHolder.h',
             'testing/GCObservation.cpp',
             'testing/GCObservation.h',
             'testing/InternalProfilers.cpp',
             'testing/InternalProfilers.h',
             'testing/InternalSettings.cpp',
             'testing/InternalSettings.h',
             'testing/Internals.cpp',
             'testing/Internals.h',
@@ skipping 85 matching lines @@
             'loader/MixedContentCheckerTest.cpp',
             'page/NetworkStateNotifierTest.cpp',
             'rendering/RenderOverflowTest.cpp',
             'rendering/shapes/BoxShapeTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }