Fix a failure to correctly set the static type on a frame element at a...

src/virtual-frame.cc

Index: src/virtual-frame.cc
===================================================================
--- src/virtual-frame.cc	(revision 1985)
+++ src/virtual-frame.cc	(working copy)
@@ -307,11 +307,12 @@
 void VirtualFrame::PrepareForReturn() {
   // Spill all locals. This is necessary to make sure all locals have
   // the right value when breaking at the return site in the debugger.
-  //
-  // TODO(203): It is also necessary to ensure that merging at the
-  // return site does not generate code to overwrite eax, where the
-  // return value is kept in a non-refcounted register reference.
-  for (int i = 0; i < expression_base_index(); i++) SpillElementAt(i);
+  // Set their static type to unknown so that they will match the known
+  // return frame.
+  for (int i = 0; i < expression_base_index(); i++) {
+    SpillElementAt(i);
+    elements_[i].set_static_type(StaticType::unknown());
+  }
 }