[objcmt] Fix a mishandled conversion to objc directory literal.

rdar://13181413

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178942 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Edit/EditedSource.cpp b/lib/Edit/EditedSource.cpp
index dd99ca9..34b5e62 100644
--- a/lib/Edit/EditedSource.cpp
+++ b/lib/Edit/EditedSource.cpp
@@ -188,6 +188,8 @@
     unsigned diff = EndOffs.getOffset() - TopEnd.getOffset();
     TopEnd = EndOffs;
     TopFA->RemoveLen += diff;
+    if (B == BeginOffs)
+      TopFA->Text = StringRef();
     ++I;
   }