Fixed a bug that allowed reading to an integer format from a non-integer frame buffer.

src/libGLESv2/libGLESv2.cpp

@@ -1587,7 +1587,16 @@ bool validES3ReadFormatType(GLenum internalFormat, GLenum format, GLenum type)
         switch (type)
         {
           case GL_INT:
+            if (!gl::IsSignedIntegerFormat(internalFormat, 3))
+            {
+                return false;
+            }
+            break;
           case GL_UNSIGNED_INT:
+            if (!gl::IsUnsignedIntegerFormat(internalFormat, 3))
+            {
+                return false;
+            }
             break;
           default:
             return false;