Improve error message for duplicate parameters

src/messages.h

Index: src/messages.h
diff --git a/src/messages.h b/src/messages.h
index a27078e04626841a20cd707e7160f02bad7346af..acc8c6b9d5ed5663af069961cc7cb0711e30adde 100644
--- a/src/messages.h
+++ b/src/messages.h
@@ -297,8 +297,6 @@ class CallSite {
   T(ConstructorIsGenerator, "Class constructor may not be a generator")        \
   T(DerivedConstructorReturn,                                                  \
     "Derived constructors may only return object or undefined")                \
-  T(DuplicateArrawFunFormalParam,                                              \
-    "Arrow function may not have duplicate parameter names")                   \
   T(DuplicateConstructor, "A class may only have one constructor")             \
   T(DuplicateExport, "Duplicate export of '%'")                                \
   T(DuplicateProto,                                                            \
@@ -335,6 +333,7 @@ class CallSite {
   T(ParamAfterRest, "Rest parameter must be last formal parameter")            \
   T(BadSetterRestParameter,                                                    \
     "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(SingleFunctionLiteral, "Single function literal required")                 \
   T(SloppyLexical,                                                             \
@@ -346,8 +345,6 @@ class CallSite {
     "In strict mode code, functions can only be declared at top level or "     \
     "immediately within another function.")                                    \
   T(StrictOctalLiteral, "Octal literals are not allowed in strict mode.")      \
-  T(StrictParamDupe,                                                           \
-    "Strict mode function may not have duplicate parameter names")             \
   T(StrictWith, "Strict mode code may not include a with statement")           \
   T(StrongArguments,                                                           \
     "In strong mode, 'arguments' is deprecated, use '...args' instead")        \