Fix bug where strings were not flattened before regexp.

src/objects.h

Index: src/objects.h
===================================================================
--- src/objects.h	(revision 1138)
+++ src/objects.h	(working copy)
@@ -3131,16 +3131,18 @@
   // to this method are not efficient unless the string is flat.
   inline uint16_t Get(StringShape shape, int index);
 
-  // Flatten the top level ConsString that is hiding behind this
+  // Try to flatten the top level ConsString that is hiding behind this
   // string.  This is a no-op unless the string is a ConsString or a
   // SlicedString.  Flatten mutates the ConsString and might return a
   // failure.
-  Object* Flatten(StringShape shape);
-  // Try to flatten the string.  Do not allow handling of allocation
-  // failures.  After calling TryFlatten, the string could still be a
-  // ConsString.
-  inline void TryFlatten(StringShape shape);
+  Object* TryFlatten(StringShape shape);
 
+  // Try to flatten the string.  Checks first inline to see if it is necessary.
+  // Do not handle allocation failures.  After calling TryFlattenIfNotFlat, the
+  // string could still be a ConsString, in which case a failure is returned.
+  // Use FlattenString from Handles.cc to be sure to flatten.
+  inline Object* TryFlattenIfNotFlat(StringShape shape);
+
   Vector<const char> ToAsciiVector();
   Vector<const uc16> ToUC16Vector();