Avoid some work on SkClipStack equality when the topmost genids match

src/core/SkClipStack.cpp

Index: src/core/SkClipStack.cpp
diff --git a/src/core/SkClipStack.cpp b/src/core/SkClipStack.cpp
index 53a88881355038a9d36b0440d31bb75e3d03a167..c66a219b629bbe7c467eafa946e2487fe067afbe 100644
--- a/src/core/SkClipStack.cpp
+++ b/src/core/SkClipStack.cpp
@@ -406,6 +406,9 @@ SkClipStack& SkClipStack::operator=(const SkClipStack& b) {
 }
 
 bool SkClipStack::operator==(const SkClipStack& b) const {
+    if (this->getTopmostGenID() == b.getTopmostGenID()) {
+        return true;
+    }
     if (fSaveCount != b.fSaveCount ||
         fDeque.count() != b.fDeque.count()) {
         return false;