Add support for skew()

Change-Id: Ia3a9a867f74fd78b61f75179e3788fdc2f0cacd0
diff --git a/core/java/android/view/GLES20Canvas.java b/core/java/android/view/GLES20Canvas.java
index 5fac525..99b686e 100644
--- a/core/java/android/view/GLES20Canvas.java
+++ b/core/java/android/view/GLES20Canvas.java
@@ -374,16 +374,18 @@
 
     @Override
     public void translate(float dx, float dy) {
-        nTranslate(mRenderer, dx, dy);
+        if (dx != 0.0f || dy != 0.0f) nTranslate(mRenderer, dx, dy);
     }
     
     private native void nTranslate(int renderer, float dx, float dy);
 
     @Override
     public void skew(float sx, float sy) {
-        throw new UnsupportedOperationException();
+        nSkew(mRenderer, sx, sy);
     }
 
+    private native void nSkew(int renderer, float sx, float sy);
+
     @Override
     public void rotate(float degrees) {
         nRotate(mRenderer, degrees);