Change 'Parse error' to three more informative messages.

src/parser.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 644 matching lines @@
 
     if (ok && is_extended_mode()) {
       CheckConflictingVarDeclarations(top_scope_, &ok);
     }
 
     if (ok && info->parse_restriction() == ONLY_SINGLE_FUNCTION_LITERAL) {
       if (body->length() != 1 ||
           !body->at(0)->IsExpressionStatement() ||
           !body->at(0)->AsExpressionStatement()->
               expression()->IsFunctionLiteral()) {
-        ReportMessage("unable_to_parse", Vector<const char*>::empty());
+        ReportMessage("single_function_literal", Vector<const char*>::empty());
         ok = false;
       }
     }
 
     if (ok) {
       result = factory()->NewFunctionLiteral(
           no_name,
           top_scope_,
           body,
           function_state.materialized_literal_count(),
@@ skipping 4069 matching lines @@
   // Check for built-in IS_VAR macro.
   if (function != NULL &&
       function->intrinsic_type == Runtime::RUNTIME &&
       function->function_id == Runtime::kIS_VAR) {
     // %IS_VAR(x) evaluates to x if x is a variable,
     // leads to a parse error otherwise.  Could be implemented as an
     // inline function %_IS_VAR(x) to eliminate this special case.
     if (args->length() == 1 && args->at(0)->AsVariableProxy() != NULL) {
       return args->at(0);
     } else {
-      ReportMessage("unable_to_parse", Vector<const char*>::empty());
+      ReportMessage("not_isvar", Vector<const char*>::empty());
       *ok = false;
       return NULL;
     }
   }
 
   // Check that the expected number of arguments are being passed.
   if (function != NULL &&
       function->nargs != -1 &&
       function->nargs != args->length()) {
     ReportMessage("illegal_access", Vector<const char*>::empty());
@@ skipping 1270 matching lines @@
       ASSERT(info()->isolate()->has_pending_exception());
     } else {
       result = ParseProgram();
     }
   }
   info()->SetFunction(result);
   return (result != NULL);
 }
 
 } }  // namespace v8::internal