probable fix for asan bot

NOTREECHECKS=True
TBR=bsalomon@google.com
BUG=skia:

Review URL: https://codereview.chromium.org/956583002

include/gpu/GrClip.h

@@ -93,6 +93,7 @@ public:
     }
 
     void setClipStack(const SkClipStack* clipStack, const SkIPoint* origin = NULL) {
+        this->reset();
         if (clipStack->isWideOpen()) {
             fClipType = kWideOpen_ClipType;
             fOrigin.setZero();

src/gpu/GrClip.cpp

@@ -50,6 +50,6 @@ void GrClip::getConservativeBounds(int width, int height, SkIRect* devResult,
 }
 
 const GrClip& GrClip::WideOpen() {
-    static GrClip clip;
+    static const GrClip clip;
     return clip;
 }