[Editing][CodeHealth] Extract new FrameCaret class from FrameSelection

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 1450 matching lines @@
             'editing/EditingBehavior.h',
             'editing/EditingStrategy.cpp',
             'editing/EditingStrategy.h',
             'editing/EditingStyle.cpp',
             'editing/EditingUtilities.cpp',
             'editing/EditingUtilities.h',
             'editing/Editor.cpp',
             'editing/EditorKeyBindings.cpp',
             'editing/EphemeralRange.cpp',
             'editing/EphemeralRange.h',
+            'editing/FrameCaret.cpp',
+            'editing/FrameCaret.h',
             'editing/FrameSelection.cpp',
             'editing/GranularityStrategy.cpp',
             'editing/InputMethodController.cpp',
             'editing/InputMethodController.h',
             'editing/PendingSelection.cpp',
             'editing/PendingSelection.h',
             'editing/PlainTextRange.cpp',
             'editing/PlainTextRange.h',
             'editing/Position.cpp',
             'editing/Position.h',
@@ skipping 2645 matching lines @@
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'timing/PerformanceBaseTest.cpp',
             'timing/PerformanceObserverTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'workers/WorkerThreadTestHelper.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }