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 b3e55cac226086e68d6ca1f3f6fe96913bee0884..2bf0de09f67f49964034fd9de6a8103028075755 100644
--- a/src/messages.h
+++ b/src/messages.h
@@ -581,6 +581,7 @@ 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(ExpectedEndOfParameters, "Expected arg string to end here")                \
   T(RuntimeWrongNumArgs, "Runtime function given wrong number of arguments")   \
   T(SingleFunctionLiteral, "Single function literal required")                 \
   T(SloppyFunction,                                                            \