fix dm crash

TBR=bsalomon@google.com
BUG=skia:

Review URL: https://codereview.chromium.org/1149243006
diff --git a/src/gpu/GrInOrderDrawBuffer.cpp b/src/gpu/GrInOrderDrawBuffer.cpp
index 99725a5..2a2b5b6 100644
--- a/src/gpu/GrInOrderDrawBuffer.cpp
+++ b/src/gpu/GrInOrderDrawBuffer.cpp
@@ -10,7 +10,7 @@
 // We will use the reordering buffer, unless we have NVPR.
 // TODO move NVPR to batch so we can reorder
 static inline bool allow_reordering(const GrCaps* caps) {
-    return !caps->shaderCaps()->pathRenderingSupport();
+    return caps && caps->shaderCaps() && !caps->shaderCaps()->pathRenderingSupport();
 }
 
 GrInOrderDrawBuffer::GrInOrderDrawBuffer(GrContext* context)