Fix BOM handling in TextResourceDecoder on partial data

third_party/WebKit/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 4145 matching lines @@
             'html/parser/AtomicHTMLTokenTest.cpp',
             'html/parser/CompactHTMLTokenTest.cpp',
             'html/parser/HTMLEntityParserTest.cpp',
             'html/parser/HTMLParserIdiomsTest.cpp',
             'html/parser/HTMLParserThreadTest.cpp',
             'html/parser/HTMLPreloadScannerTest.cpp',
             'html/parser/HTMLResourcePreloaderTest.cpp',
             'html/parser/HTMLSrcsetParserTest.cpp',
             'html/parser/HTMLTokenizerTest.cpp',
             'html/parser/HTMLTreeBuilderSimulatorTest.cpp',
+            'html/parser/TextResourceDecoderTest.cpp',
             'html/shadow/MediaControlsTest.cpp',
             'html/track/TextTrackListTest.cpp',
             'html/track/vtt/BufferedLineReaderTest.cpp',
             'html/track/vtt/VTTScannerTest.cpp',
             'input/EventHandlerTest.cpp',
             'layout/ImageQualityControllerTest.cpp',
             'layout/InlineTextBoxTest.cpp',
             'layout/LayoutBlockTest.cpp',
             'layout/LayoutBoxModelObjectTest.cpp',
             'layout/LayoutBoxTest.cpp',
@@ skipping 62 matching lines @@
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'timing/PerformanceBaseTest.cpp',
             'timing/PerformanceObserverTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'workers/WorkerThreadTestHelper.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }