Fix rdar://5919567: assertion failure: split didn't occur before erase!


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@50839 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Rewrite/RewriteRope.cpp b/lib/Rewrite/RewriteRope.cpp
index 7ee9fcc..9d5d7a7 100644
--- a/lib/Rewrite/RewriteRope.cpp
+++ b/lib/Rewrite/RewriteRope.cpp
@@ -567,10 +567,12 @@
       unsigned BytesFromChild = CurChild->size()-Offset;
       CurChild->erase(Offset, BytesFromChild);
       NumBytes -= BytesFromChild;
+      // Start at the beginning of the next child.
+      Offset = 0;
       ++i;
       continue;
     }
-    
+
     // If the deletion request completely covers the child, delete it and move
     // the rest down.
     NumBytes -= CurChild->size();