Revert of Update SkPicture cull rects with RTree information

src/core/SkRTree.cpp

Index: src/core/SkRTree.cpp
diff --git a/src/core/SkRTree.cpp b/src/core/SkRTree.cpp
index 2fded6f72bd396be27b3e49d7614639bab99937e..ba5843e537eaba6b3f90862132e5c0dc29d7f77e 100644
--- a/src/core/SkRTree.cpp
+++ b/src/core/SkRTree.cpp
@@ -8,14 +8,6 @@
 #include "SkRTree.h"
 
 SkRTree::SkRTree(SkScalar aspectRatio) : fCount(0), fAspectRatio(aspectRatio) {}
-
-SkRect SkRTree::getRootBound() const {
-    if (fCount) {
-        return fRoot.fBounds;
-    } else {
-        return SkRect::MakeEmpty();
-    }
-}
 
 void SkRTree::insert(const SkRect boundsArray[], int N) {
     SkASSERT(0 == fCount);