Defer early-exit due to zero-sized copies until after all other validation for CopyTex*Image.

TRAC #20925

Signed-off-by: Jamie Madill
Signed-off-by: Shannon Woods
diff --git a/src/libGLESv2/validationES3.cpp b/src/libGLESv2/validationES3.cpp
index 0e9d48d..e8df0ac 100644
--- a/src/libGLESv2/validationES3.cpp
+++ b/src/libGLESv2/validationES3.cpp
@@ -337,11 +337,6 @@
         return gl::error(GL_INVALID_VALUE, false);
     }
 
-    if (width == 0 || height == 0)
-    {
-        return false;
-    }
-
     if (border != 0)
     {
         return gl::error(GL_INVALID_VALUE, false);
@@ -488,7 +483,8 @@
         }
     }
 
-    return true;
+    // If width or height is zero, it is a no-op.  Return false without setting an error.
+    return (width > 0 && height > 0);
 }
 
 bool ValidateES3TexStorageParameters(gl::Context *context, GLenum target, GLsizei levels, GLenum internalformat,