StringImpl should not be referred from StringImplCF.

Source/wtf/wtf.gypi

 {
     'variables': {
         'wtf_files': [
             'ASCIICType.h',
             'Alignment.h',
             'ArrayBuffer.cpp',
             'ArrayBuffer.h',
             'ArrayBufferBuilder.cpp',
             'ArrayBufferBuilder.h',
             'ArrayBufferContents.cpp',
@@ skipping 155 matching lines @@
             'dtoa/fast-dtoa.cc',
             'dtoa/fast-dtoa.h',
             'dtoa/fixed-dtoa.cc',
             'dtoa/fixed-dtoa.h',
             'dtoa/strtod.cc',
             'dtoa/strtod.h',
             'dtoa/utils.h',
             'text/ASCIIFastPath.h',
             'text/AtomicString.cpp',
             'text/AtomicString.h',
-            'text/AtomicStringCF.cpp',
             'text/AtomicStringHash.h',
             'text/Base64.cpp',
             'text/Base64.h',
             'text/CString.cpp',
             'text/CString.h',
             'text/IntegerToStringConversion.h',
             'text/StringBuffer.h',
             'text/StringBuilder.cpp',
             'text/StringBuilder.h',
             'text/StringCF.cpp',
@@ skipping 55 matching lines @@
             'text/TextCodecUTF8Test.cpp',
             'text/WTFStringTest.cpp',
         ],
         'wtf_unittest_helper_files': [
             'testing/WTFTestHelpers.cpp',
             'testing/WTFTestHelpers.h',
             'testing/WTFUnitTestHelpersExport.h',
         ],
     },
 }