CC Animation: Expose TargetProperty enum to be aliased in Blink Platform.

TargetProperty is intended to be used as an alias in Source/platform/animation/CompositorTargetProperty.h

This is slightly better then untyped approach used here:
https://codereview.chromium.org/1599673002
where we setup struct with constants in it and pass uint32_t everywhere.

An alternative approach with strongly typed enum
considered too verbose:
https://codereview.chromium.org/1698813002/

BUG=577016
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1700653002

Cr-Commit-Position: refs/heads/master@{#377501}

• cc/BUILD.gn[diff]
• cc/animation/animation.cc[diff]
• cc/animation/animation.h[diff]
• cc/animation/animation_delegate.h[diff]
• cc/animation/animation_events.cc[diff]
• cc/animation/animation_events.h[diff]
• cc/animation/animation_host.cc[diff]
• cc/animation/animation_host.h[diff]
• cc/animation/animation_player.cc[diff]
• cc/animation/animation_player.h[diff]
• cc/animation/animation_player_unittest.cc[diff]
• cc/animation/animation_unittest.cc[diff]
• cc/animation/element_animations.cc[diff]
• cc/animation/element_animations.h[diff]
• cc/animation/layer_animation_controller.cc[diff]
• cc/animation/layer_animation_controller.h[diff]
• cc/animation/layer_animation_controller_unittest.cc[diff]
• cc/animation/target_property.cc[Added - diff]
• cc/animation/target_property.h[Added - diff]
• cc/blink/web_to_cc_animation_delegate_adapter.cc[diff]
• cc/blink/web_to_cc_animation_delegate_adapter.h[diff]
• cc/cc.gyp[diff]
• cc/layers/layer.cc[diff]
• cc/layers/layer.h[diff]
• cc/layers/layer_impl.cc[diff]
• cc/layers/layer_impl.h[diff]
• cc/layers/layer_unittest.cc[diff]
• cc/test/animation_test_common.cc[diff]
• cc/test/animation_test_common.h[diff]
• cc/test/animation_timelines_test_common.cc[diff]
• cc/test/animation_timelines_test_common.h[diff]
• cc/test/test_hooks.h[diff]
• cc/trees/layer_tree_host.cc[diff]
• cc/trees/layer_tree_host.h[diff]
• cc/trees/layer_tree_host_common_unittest.cc[diff]
• cc/trees/layer_tree_host_impl.cc[diff]
• cc/trees/layer_tree_host_impl_unittest.cc[diff]
• cc/trees/layer_tree_host_unittest_animation.cc[diff]
• cc/trees/layer_tree_host_unittest_animation_timelines.cc[diff]
• cc/trees/layer_tree_impl.cc[diff]
• cc/trees/layer_tree_impl.h[diff]
• cc/trees/property_tree_builder.cc[diff]
• third_party/WebKit/Source/core/animation/CompositorAnimations.cpp[diff]
• third_party/WebKit/Source/core/animation/CompositorAnimationsTest.cpp[diff]
• third_party/WebKit/Source/core/animation/CompositorAnimationsTestHelper.h[diff]
• third_party/WebKit/Source/platform/animation/CompositorAnimation.cpp[diff]
• third_party/WebKit/Source/platform/animation/CompositorAnimation.h[diff]
• third_party/WebKit/Source/platform/animation/CompositorAnimationPlayer.cpp[diff]
• third_party/WebKit/Source/platform/animation/CompositorAnimationPlayer.h[diff]
• third_party/WebKit/Source/platform/animation/CompositorAnimationPlayerTest.cpp[diff]
• third_party/WebKit/Source/platform/animation/CompositorAnimationTest.cpp[diff]
• third_party/WebKit/Source/platform/animation/CompositorTargetProperty.h[Added - diff]
• third_party/WebKit/Source/platform/blink_platform.gypi[diff]
• third_party/WebKit/Source/platform/graphics/CompositorFactory.cpp[diff]
• third_party/WebKit/Source/platform/graphics/CompositorFactory.h[diff]
• third_party/WebKit/Source/platform/graphics/GraphicsLayerTest.cpp[diff]
• third_party/WebKit/Source/platform/scroll/ProgrammaticScrollAnimator.cpp[diff]
• third_party/WebKit/Source/platform/scroll/ScrollAnimator.cpp[diff]
• third_party/WebKit/Source/web/LinkHighlightImpl.cpp[diff]
• ui/compositor/layer_animation_element.cc[diff]
• ui/compositor/layer_animation_element.h[diff]
• ui/compositor/layer_animation_sequence_unittest.cc[diff]
• ui/compositor/layer_animator_unittest.cc[diff]
• ui/compositor/test/layer_animator_test_controller.cc[diff]