Implement new Function.prototype.toString and fix CreateDynamicFunction parsing

src/messages.h

Index: src/messages.h
diff --git a/src/messages.h b/src/messages.h
index 814470cd57ebd7dc11af57748288ee978fd93180..bb595c2f8a50710d3925481236a8de24823aa8d4 100644
--- a/src/messages.h
+++ b/src/messages.h
@@ -593,6 +593,9 @@ class ErrorUtils : public AllStatic {
     "Setter function argument must not be a rest parameter")                   \
   T(ParamDupe, "Duplicate parameter name not allowed in this context")         \
   T(ParenthesisInArgString, "Function arg string contains parenthesis")        \
+  T(ArgStringTerminatesParametersEarly,                                        \
+    "Arg string terminates parameters early")                                  \
+  T(UnexpectedEndOfArgString, "Unexpected end of arg string")                  \
   T(RuntimeWrongNumArgs, "Runtime function given wrong number of arguments")   \
   T(SingleFunctionLiteral, "Single function literal required")                 \
   T(SloppyFunction,                                                            \