Move AbstractInlineTextBox to line/ sub-directory.

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 516 matching lines @@
             'events/WebKitAnimationEvent.idl',
             'events/WheelEvent.idl',
             'html/MediaKeyEvent.idl',
             'html/canvas/WebGLContextEvent.idl',
             'html/track/TrackEvent.idl',
             'storage/StorageEvent.idl',
             'svg/SVGZoomEvent.idl',
             'xmlhttprequest/XMLHttpRequestProgressEvent.idl',
         ],
         'webcore_rendering_files': [
-            'layout/AbstractInlineTextBox.cpp',
-            'layout/AbstractInlineTextBox.h',
             'layout/BidiRun.h',
             'layout/BidiRunForLine.cpp',
             'layout/BidiRunForLine.h',
             'layout/ClipRect.cpp',
             'layout/ClipRect.h',
             'layout/ClipRects.h',
             'layout/ClipRectsCache.h',
             'layout/CounterNode.cpp',
             'layout/CounterNode.h',
             'layout/FilterEffectRenderer.cpp',
@@ skipping 101 matching lines @@
             'layout/compositing/CompositingRequirementsUpdater.cpp',
             'layout/compositing/CompositingRequirementsUpdater.h',
             'layout/compositing/CompositingState.h',
             'layout/compositing/CompositingTriggers.h',
             'layout/compositing/GraphicsLayerTreeBuilder.cpp',
             'layout/compositing/GraphicsLayerTreeBuilder.h',
             'layout/compositing/GraphicsLayerUpdater.cpp',
             'layout/compositing/GraphicsLayerUpdater.h',
             'layout/compositing/LayerCompositor.cpp',
             'layout/compositing/LayerCompositor.h',
+            'layout/line/AbstractInlineTextBox.cpp',
+            'layout/line/AbstractInlineTextBox.h',
             'layout/line/BreakingContext.cpp',
             'layout/line/EllipsisBox.cpp',
             'layout/line/EllipsisBox.h',
             'layout/line/FloatToLayoutUnit.h',
             'layout/line/InlineBox.cpp',
             'layout/line/InlineFlowBox.cpp',
             'layout/line/InlineIterator.h',
             'layout/line/InlineTextBox.cpp',
             'layout/line/LineBreaker.cpp',
             'layout/line/LineBreaker.h',
@@ skipping 3104 matching lines @@
             'rendering/style/SVGRenderStyleTest.cpp',
             'streams/ExclusiveStreamReaderTest.cpp',
             'streams/ReadableStreamTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }