Allow using a larger-than-necessary texture as cached render pass backing

cc/shader.h

Index: cc/shader.h
diff --git a/cc/shader.h b/cc/shader.h
index 67e93cbcf09e2010b017111733941ab166eeb956..a1aec88d69298193d883e15bc8ea05d9c8daa2c3 100644
--- a/cc/shader.h
+++ b/cc/shader.h
@@ -85,10 +85,12 @@ public:
 
     int matrixLocation() const { return m_matrixLocation; }
     int pointLocation() const { return m_pointLocation; }
+    int texScaleLocation() const { return m_texScaleLocation; }
 
 private:
     int m_matrixLocation;
     int m_pointLocation;
+    int m_texScaleLocation;
 };
 
 class VertexShaderTile {