Adding a reverse function to the TimingFunctions and tests to prove it works.

Source/core/platform/animation/TimingFunctionTest.cpp

Index: Source/core/platform/animation/TimingFunctionTest.cpp
diff --git a/Source/core/platform/animation/TimingFunctionTest.cpp b/Source/core/platform/animation/TimingFunctionTest.cpp
index 2cd17c3751c4ad81293f291d30b02de45d341385..5e0e21cf1151c1dea236524d7c637289dbd1053c 100644
--- a/Source/core/platform/animation/TimingFunctionTest.cpp
+++ b/Source/core/platform/animation/TimingFunctionTest.cpp
@@ -64,7 +64,6 @@
         } \
     }
 
-
 using namespace WebCore;
 
 namespace {
@@ -260,4 +259,59 @@ TEST_F(TimingFunctionTest, ChainedEq)
     EXPECT_REFV_NE(chainedMixed1, chainedMixed4);
 }
 
+TEST_F(TimingFunctionTest, LinearReverse)
+{
+    RefPtr<TimingFunction> linearTiming = LinearTimingFunction::create();
+    EXPECT_REFV_EQ(linearTiming, linearTiming->reverse());
+}
+
+TEST_F(TimingFunctionTest, CubicReverse)
+{
+    RefPtr<TimingFunction> cubicEaseInTiming = CubicBezierTimingFunction::preset(CubicBezierTimingFunction::EaseIn);
+    RefPtr<TimingFunction> cubicEaseOutTiming = CubicBezierTimingFunction::preset(CubicBezierTimingFunction::EaseOut);
+    RefPtr<TimingFunction> cubicEaseInOutTiming = CubicBezierTimingFunction::preset(CubicBezierTimingFunction::EaseInOut);
+
+    EXPECT_REFV_EQ(cubicEaseOutTiming, cubicEaseInTiming->reverse());
+    EXPECT_REFV_EQ(cubicEaseInTiming, cubicEaseOutTiming->reverse());
+    EXPECT_REFV_EQ(cubicEaseInOutTiming, cubicEaseInOutTiming->reverse());
+
+    RefPtr<TimingFunction> cubicCustomTiming = CubicBezierTimingFunction::create(0.17, 0.67, 1, -1.73);
+    RefPtr<TimingFunction> cubicCustomTimingReversed = CubicBezierTimingFunction::create(0.17, 0.67, 1, -1.73);
+    EXPECT_REFV_EQ(cubicCustomTimingReversed, cubicCustomTiming->reverse());
+}
+
+TEST_F(TimingFunctionTest, StepReverse)
+{
+    RefPtr<TimingFunction> stepTimingStart = StepsTimingFunction::preset(StepsTimingFunction::Start);
+    RefPtr<TimingFunction> stepTimingEnd = StepsTimingFunction::preset(StepsTimingFunction::End);
+
+    EXPECT_REFV_EQ(stepTimingEnd, stepTimingStart->reverse());
+    EXPECT_REFV_EQ(stepTimingStart, stepTimingEnd->reverse());
+
+    RefPtr<TimingFunction> stepTimingCustom = StepsTimingFunction::create(5, false);
+    RefPtr<TimingFunction> stepTimingCustomReversed = StepsTimingFunction::create(5, true);
+    EXPECT_REFV_EQ(stepTimingCustomReversed, stepTimingCustom);
+}
+
+TEST_F(TimingFunctionTest, ChainedReverse)
+{
+    RefPtr<TimingFunction> linearTiming = LinearTimingFunction::create();
+    RefPtr<ChainedTimingFunction> chainedLinearSingle = ChainedTimingFunction::create();
+    chainedLinearSingle->appendSegment(1.0, linearTiming.get());
+    EXPECT_REFV_EQ(chainedLinearSingle, chainedLinearSingle->reverse());
+
+    RefPtr<TimingFunction> cubicEaseInTiming = CubicBezierTimingFunction::preset(CubicBezierTimingFunction::EaseIn);
+    RefPtr<TimingFunction> cubicEaseOutTiming = CubicBezierTimingFunction::preset(CubicBezierTimingFunction::EaseOut);
+
+    RefPtr<ChainedTimingFunction> chainedMixed = ChainedTimingFunction::create();
+    chainedMixed->appendSegment(0.75, chainedLinearSingle.get());
+    chainedMixed->appendSegment(1.0, cubicEaseInTiming.get());
+
+    RefPtr<ChainedTimingFunction> chainedMixedReversed = ChainedTimingFunction::create();
+    chainedMixed->appendSegment(0.25, cubicEaseOutTiming.get());
+    chainedMixed->appendSegment(1.0, chainedLinearSingle.get());
+
+    EXPECT_REFV_EQ(chainedMixed, chainedMixedReversed);
+}
+
 } // namespace