Move fetch-related predicates to core/fetch.

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/AnimationPlayer.idl',
@@ skipping 1072 matching lines @@
             'fetch/CrossOriginAccessControl.cpp',
             'fetch/CrossOriginAccessControl.h',
             'fetch/DocumentResource.cpp',
             'fetch/DocumentResource.h',
             'fetch/DocumentResourceReference.h',
             'fetch/FetchContext.cpp',
             'fetch/FetchContext.h',
             'fetch/FetchInitiatorInfo.h',
             'fetch/FetchRequest.cpp',
             'fetch/FetchRequest.h',
+            'fetch/FetchUtils.cpp',
+            'fetch/FetchUtils.h',
             'fetch/FontResource.cpp',
             'fetch/FontResource.h',
             'fetch/ImageResource.cpp',
             'fetch/ImageResource.h',
             'fetch/MemoryCache.cpp',
             'fetch/MemoryCache.h',
             'fetch/RawResource.cpp',
             'fetch/RawResource.h',
             'fetch/Resource.cpp',
             'fetch/Resource.h',
@@ skipping 2347 matching lines @@
             'rendering/shapes/BoxShapeTest.cpp',
             'rendering/style/OutlineValueTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'streams/ReadableStreamTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }