Composited Animations: Introduce pixel-ref layout tests.

LayoutTests/animations/resources/composited-animations-data/timing-function.js

Index: LayoutTests/animations/resources/composited-animations-data/timing-function.js
diff --git a/LayoutTests/animations/resources/composited-animations-data/timing-function.js b/LayoutTests/animations/resources/composited-animations-data/timing-function.js
new file mode 100644
index 0000000000000000000000000000000000000000..785efed65edb93fd4a52eaa9a13085e5ccdf4e7d
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+++ b/LayoutTests/animations/resources/composited-animations-data/timing-function.js
@@ -0,0 +1,72 @@
+var translateSteps = {
+  keyframes: [
+    {transform: 'translateX(100px)'},
+    {transform: 'translateX(500px)'}
+  ],
+  easing: 'steps(9)',
+  style: `background: maroon; float: none;`,
+  samples: [
+    {at: 0},
+    {at: 0.25},
+    {at: 0.5},
+    {at: 0.75},
+    {at: 1.1},
+  ]
+};
+
+var translateStepsPerKeyframe = {
+  keyframes: [
+    {transform: 'translateX(100px)', easing: 'steps(18)'},
+    {transform: 'translateX(400px)', easing: 'steps(9)'},
+    {transform: 'translateX(500px)'}
+  ],
+  style: `background: navy; float: none;`,
+  samples: [
+    {at: 0},
+    {at: 0.25},
+    {at: 0.35},
+    {at: 0.5},
+    {at: 0.65},
+    {at: 0.75},
+    {at: 1.1},
+  ]
+};
+
+var translateStepsWithCubicBezier = {
+  keyframes: [
+    {transform: 'translateX(100px)', easing: 'steps(9)'},
+    {transform: 'translateX(500px)'}
+  ],
+  easing: 'cubic-bezier(.5, -1, .5, 2)',
+  style: `background: black; float: none;`,
+  samples: [
+    {at: 0},
+    {at: 0.4},
+    {at: 0.45},
+    {at: 0.5},
+    {at: 0.6},
+    {at: 1.41},
+  ]
+};
+
+var translateCubicBezierWithSteps = {
+  keyframes: [
+    {transform: 'translateX(100px)', easing: 'cubic-bezier(.5, -1, .5, 2)'},
+    {transform: 'translateX(500px)'}
+  ],
+  easing: 'steps(9)',
+  style: `background: peru; float: none;`,
+  samples: [
+    {at: 0},
+    {at: 0.25},
+    {at: 0.35},
+    {at: 0.5},
+    {at: 0.65},
+    {at: 0.75},
+    {at: 1.39},
+  ]
+};
+
+var timingFunctionTests = [translateSteps, translateStepsPerKeyframe,
+                           translateStepsWithCubicBezier, translateCubicBezierWithSteps];
+