Move MessageLocations constructor out of header

src/messages.h

Index: src/messages.h
diff --git a/src/messages.h b/src/messages.h
index da9637b9410c18ebfe6a8bd5cec5d8303e04d94a..9edaceee865e23b8f5931987155afb9a02a01c0d 100644
--- a/src/messages.h
+++ b/src/messages.h
@@ -24,13 +24,10 @@ class SourceInfo;
 
 class MessageLocation {
  public:
+  MessageLocation(Handle<Script> script, int start_pos, int end_pos);
   MessageLocation(Handle<Script> script, int start_pos, int end_pos,
-                  Handle<JSFunction> function = Handle<JSFunction>())
-      : script_(script),
-        start_pos_(start_pos),
-        end_pos_(end_pos),
-        function_(function) {}
-  MessageLocation() : start_pos_(-1), end_pos_(-1) { }
+                  Handle<JSFunction> function);
+  MessageLocation();
 
   Handle<Script> script() const { return script_; }
   int start_pos() const { return start_pos_; }