Add direct getter for GrCaps to GrContext.

TBR=joshualitt@google.com

Committed: https://skia.googlesource.com/skia/+/9138c46e572085870638b6f7ad7fcdfcdf3cac99

Review URL: https://codereview.chromium.org/1149773005
diff --git a/tests/GrPorterDuffTest.cpp b/tests/GrPorterDuffTest.cpp
index 3146712..41a8b5a 100644
--- a/tests/GrPorterDuffTest.cpp
+++ b/tests/GrPorterDuffTest.cpp
@@ -949,7 +949,7 @@
         return;
     }
 
-    const GrCaps& caps = *ctx->getGpu()->caps();
+    const GrCaps& caps = *ctx->caps();
     if (caps.shaderCaps()->dualSourceBlendingSupport()) {
         SkFAIL("Null context failed to honor request for no ARB_blend_func_extended.");
         return;