Bug 770956. Use LINEAR instead of NEAREST. r=chrislord

Sometimes screenshots are MAGNIFIED in one axis and MINIFIED in the other. This
makes it so we use consistent filtering in both directions.

--HG--
extra : rebase_source : 0d9d1ff98d3b48fb817edf872aadaed4329d3126

mobile/android/base/gfx/TileLayer.java

@@ -154,7 +154,7 @@ public abstract class TileLayer extends Layer {
         GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
         GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, mTextureIDs[0]);
         GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER,
-                               GLES20.GL_NEAREST);
+                               GLES20.GL_LINEAR);
         GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER,
                                GLES20.GL_LINEAR);