Reland "UTF-8 detector for pages missing encoding info"

third_party/WebKit/Source/wtf/wtf.gypi

 # For GN compatibility, this file can not have any conditions.
 {
     'variables': {
         'wtf_files': [
             'ASCIICType.cpp',
             'ASCIICType.h',
             'AddressSanitizer.h',
             'Alignment.h',
             'Allocator.h',
             'Assertions.cpp',
@@ skipping 207 matching lines @@
             'allocator/PartitionAllocTest.cpp',
             'dtoa_test.cpp',
             'text/AtomicStringTest.cpp',
             'text/CStringTest.cpp',
             'text/StringBufferTest.cpp',
             'text/StringBuilderTest.cpp',
             'text/StringImplTest.cpp',
             'text/StringOperatorsTest.cpp',
             'text/TextCodecReplacementTest.cpp',
             'text/TextCodecUTF8Test.cpp',
+            "text/UTF8Test.cpp",
             'text/WTFStringTest.cpp',
             'typed_arrays/ArrayBufferBuilderTest.cpp',
         ],
     },
 }