Add getFrameData and getPose layout tests

third_party/WebKit/LayoutTests/vr/resources/test-constants.js

 // assert_equals can fail when comparing floats due to precision errors, so
 // use assert_approx_equals with this constant instead
 var FLOAT_EPSILON = 0.0000001;
+
+// A valid VRPose for when we don't care about specific values
+var VALID_POSE = {
+  position: [1.1, 2.2, 3.3],
+  linearVelocity: [0.1, 0.2, 0.3],
+  linearAcceleration: [0.0, 0.1, 0.2],
+  orientation: [0.1, 0.2, 0.3, 0.4],
+  angularVelocity: [1.1, 2.1, 3.1],
+  angularAcceleration: [1.0, 2.0, 3.0]
+}