Fix tautological compare in GrSurfaceProxy.cpp

-1 is not a valid value for the GrSurfaceOrigin enum, and certain
versions of Clang warn that the comparison is effectively a no-op:

  ../../third_party/skia/src/gpu/GrSurfaceProxy.cpp:547:38: warning: comparison
  of constant -1 with expression of type 'GrSurfaceOrigin' is always true
  [-Wtautological-constant-out-of-range-compare]
      SkASSERT(kGrUnknownSurfaceOrigin != fProxy->origin());
	       ~~~~~~~~~~~~~~~~~~~~~~~ ^  ~~~~~~~~~~~~~~~~

Instead of trying to force -1 in there, drop the assert and initialize with
top-left as origin.

Bug: chromium:793189
Change-Id: I4cb6720d567f6c5650a19df33d3c77f2d738a516
Reviewed-on: https://skia-review.googlesource.com/82961
Reviewed-by: Chris Dalton <csmartdalton@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>

0 files changed, 0 insertions, 0 deletions