Teach ScriptRunner how to yield and post on loading task queue

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/AnimationNode.idl',
@@ skipping 3729 matching lines @@
             'css/parser/SizesAttributeParserTest.cpp',
             'css/parser/SizesCalcParserTest.cpp',
             'css/resolver/FontBuilderTest.cpp',
             'dom/ActiveDOMObjectTest.cpp',
             'dom/CrossThreadTaskTest.cpp',
             'dom/DOMImplementationTest.cpp',
             'dom/DocumentMarkerControllerTest.cpp',
             'dom/DocumentTest.cpp',
             'dom/MainThreadTaskRunnerTest.cpp',
             'dom/RangeTest.cpp',
+            'dom/ScriptRunnerTest.cpp',
             'dom/TreeScopeTest.cpp',
             'editing/CompositionUnderlineRangeFilterTest.cpp',
             'editing/FrameSelectionTest.cpp',
             'editing/InputMethodControllerTest.cpp',
             'editing/iterators/TextIteratorTest.cpp',
             'editing/SurroundingTextTest.cpp',
             'editing/VisibleSelectionTest.cpp',
             'fetch/CachingCorrectnessTest.cpp',
             'fetch/ImageResourceTest.cpp',
             'fetch/MemoryCacheTest.cpp',
@@ skipping 46 matching lines @@
             'rendering/RenderOverflowTest.cpp',
             'streams/ExclusiveStreamReaderTest.cpp',
             'streams/ReadableStreamTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }