Recursively delete rewrite rope nodes when tearing down the tree.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@154760 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Rewrite/RewriteRope.cpp b/lib/Rewrite/RewriteRope.cpp
index 6c211b2..88bf21d 100644
--- a/lib/Rewrite/RewriteRope.cpp
+++ b/lib/Rewrite/RewriteRope.cpp
@@ -407,6 +407,11 @@
       Size = LHS->size() + RHS->size();
     }
 
+    ~RopePieceBTreeInterior() {
+      Children[0]->Destroy();
+      Children[1]->Destroy();
+    }
+
     bool isFull() const { return NumChildren == 2*WidthFactor; }
 
     unsigned getNumChildren() const { return NumChildren; }