Add SkTHashSet::find()

src/core/SkTHash.h

Index: src/core/SkTHash.h
diff --git a/src/core/SkTHash.h b/src/core/SkTHash.h
index 967b9be87835be62b514daef8e13c72959f2fd0a..c4bd3b6161c2dbbbb6beeae1da12f1f869813448 100644
--- a/src/core/SkTHash.h
+++ b/src/core/SkTHash.h
@@ -231,7 +231,11 @@ public:
     void add(const T& item) { fTable.set(item); }
 
     // Is this item in the set?
-    bool contains(const T& item) const { return SkToBool(fTable.find(item)); }
+    bool contains(const T& item) const { return SkToBool(this->find(item)); }
+
+    // If an item equal to this is in the set, return a pointer to it, otherwise null.
+    // This pointer remains valid until the next call to add().
+    const T* find(const T& item) const { return fTable.find(item); }
 
 private:
     struct Traits {