[CSS Grid Layout] Introduce an explicit type for resolved grid positions

Source/core/core.gypi

 {
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/Animation.idl',
             'animation/AnimationPlayer.idl',
             'animation/TimedItem.idl',
             'animation/Timeline.idl',
             'animation/Timing.idl',
             'clipboard/DataTransfer.idl',
@@ skipping 1674 matching lines @@
             'rendering/shapes/ShapeOutsideInfo.cpp',
             'rendering/shapes/ShapeOutsideInfo.h',
             'rendering/style/BasicShapes.cpp',
             'rendering/style/BorderImageLength.h',
             'rendering/style/BorderImageLengthBox.h',
             'rendering/style/CachedUAStyle.h',
             'rendering/style/ContentData.cpp',
             'rendering/style/CounterDirectives.cpp',
             'rendering/style/FillLayer.cpp',
             'rendering/style/GridCoordinate.h',
+            'rendering/style/GridResolvedPosition.cpp',
+            'rendering/style/GridResolvedPosition.h',
             'rendering/style/KeyframeList.cpp',
             'rendering/style/KeyframeList.h',
             'rendering/style/NinePieceImage.cpp',
             'rendering/style/QuotesData.cpp',
             'rendering/style/QuotesData.h',
             'rendering/style/RenderStyle.cpp',
             'rendering/style/RenderStyle.h',
             'rendering/style/ShadowData.cpp',
             'rendering/style/ShadowData.h',
             'rendering/style/ShadowList.cpp',
@@ skipping 1668 matching lines @@
             'html/track/vtt/BufferedLineReaderTest.cpp',
             'html/track/vtt/VTTScannerTest.cpp',
             'rendering/RenderOverflowTest.cpp',
             'rendering/shapes/BoxShapeTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }