We used to have error messages which provide context, like "Variable name may
not be eval or arguments in strict mode", but for other illegal words we only
have non-context specific error messages like "Unexpected reserved word".

Providing the context makes the code unnecessarily complex, since every
individual place must remember to check for eval or arguments. This CL produces
a unified error message ("Unexpected eval or arguments in strict mode"), and puts
the error reporting to (Pre)Parser::ParseIdentifier.

Notes:

- The module feature is so experimental, that I decided to not allow "eval" or
"arguments" as module-related identifiers in the strict mode (even though this
check wasn't there before).

- Unfortunately, there were some inconsistencies, since it was the
responsibility of the caller of ParseIdentifier to check "eval" and "arguments"
and some places didn't have the check for no good reason. This CL is supposed to
keep backward compatibility and *not* introduce any new errors.

- ECMA allows "eval" and "arguments" as labels even in strict mode. (Syntax:
"LabelledStatement: Identifier : Statement", and no strict mode restrictions on
Identifier are listed.)

- Tests which compare error message strings will fail, and need to be updated.

BUG=3126
LOG=N
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/152813005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19112 ce2b1a6d-e550-0410-aec6-3dcde31c8c00