Fix shift/mask error in ArtbEvaluator

Shifting from the left copies the MSB along with it. This causes a problem
in ArgbEvaluator, which shifts the top byte down by 24 for the start/end
colors, and then uses those values to interpolate alpha values. The correct
appraoch (used with the other color components) is to mask by 0xff after the
shift.

Issue #6960514 External bug: ArgbEvaluator can't evaluate alpha value properly

Change-Id: I750d38ddfecc5f30d8dab7c6d27d1a7ac06361c3

core/java/android/animation/ArgbEvaluator.java

diff --git a/core/java/android/animation/ArgbEvaluator.java b/core/java/android/animation/ArgbEvaluator.java
index c3875be..717a3d9 100644
--- a/core/java/android/animation/ArgbEvaluator.java
+++ b/core/java/android/animation/ArgbEvaluator.java
@@ -40,13 +40,13 @@
      */
     public Object evaluate(float fraction, Object startValue, Object endValue) {
         int startInt = (Integer) startValue;
-        int startA = (startInt >> 24);
+        int startA = (startInt >> 24) & 0xff;
         int startR = (startInt >> 16) & 0xff;
         int startG = (startInt >> 8) & 0xff;
         int startB = startInt & 0xff;
 
         int endInt = (Integer) endValue;
-        int endA = (endInt >> 24);
+        int endA = (endInt >> 24) & 0xff;
         int endR = (endInt >> 16) & 0xff;
         int endG = (endInt >> 8) & 0xff;
         int endB = endInt & 0xff;