Bug fix for reduandant transpose removal:

1. this bug is a last minute check-in to replace "CHECK()" with "DCHECK()", however it turns out that "CHECK()" and "DCHECK()" are not functional equivalent;
2. unlike "CHECK()" whose expression will always be excuted, the expression in "DCHECK()" will not be executed in release mode. This causes dangling pointer failures.
3. to fix this bug, we should check the result of the expression instead of the expression itself.