Unify paren handling in (Pre)Parser::ParseExpressionOrLabelledStatement.

Unify paren handling in Parser and PreParser.

It is only needed in (Pre)Parser::ParseExpressionOrLabelledStatement for not
recognizing parenthesized identifiers as labels and in
(Pre)Parser::ParseSourceElements for not recognizing a parenthesized string as
directive prologue.

Parser Expressions don't keep track of whether they're parenthesized, so
PreParser Expressions shouldn't either.

In addition, add helper funcs for checking if an Expression is identifier or a
given identifier. (PreParser Expressions can do this.)

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

Committed: https://code.google.com/p/v8/source/detail?r=19140

[ulan, 2014-02-06 09:38:05]

lgtm

https://codereview.chromium.org/150103004/diff/30001/src/ast.h
File src/ast.h (right):

https://codereview.chromium.org/150103004/diff/30001/src/ast.h#newcode356
src/ast.h:356: bool IsIdentifierCalled(String* name);
Nit: I first understood "IsIdentifierCalled" as 'is identifier a function name
that is invoked' =) Maybe IsIdentifierNamed/IsIdentifierEquals?

https://codereview.chromium.org/150103004/diff/30001/src/preparser.cc
File src/preparser.cc (right):

https://codereview.chromium.org/150103004/diff/30001/src/preparser.cc#newcode173
src/preparser.cc:173: if (directive_prologue && peek() != Token::STRING) {
We discussed offline that the loop can be simplified. Now I got why mode
detection is in a loop. This is probably because we can have multiple
directives.

https://codereview.chromium.org/150103004/diff/30001/src/preparser.cc#newcode476
src/preparser.cc:476: if (peek() == Token::COLON && starts_with_idenfifier &&
expr.IsIdentifier()) {
Typo: starts_with_idenTifier.

Doesn't  starts_with_identifier imply expr.IsIdentifier()?

[marja, 2014-02-06 10:27:53]

Thx for review!

https://codereview.chromium.org/150103004/diff/30001/src/ast.h
File src/ast.h (right):

https://codereview.chromium.org/150103004/diff/30001/src/ast.h#newcode356
src/ast.h:356: bool IsIdentifierCalled(String* name);
On 2014/02/06 09:38:05, ulan wrote:
> Nit: I first understood "IsIdentifierCalled" as 'is identifier a function name
> that is invoked' =) Maybe IsIdentifierNamed/IsIdentifierEquals?  

Done: IsIdentifierNamed

https://codereview.chromium.org/150103004/diff/30001/src/preparser.cc
File src/preparser.cc (right):

https://codereview.chromium.org/150103004/diff/30001/src/preparser.cc#newcode173
src/preparser.cc:173: if (directive_prologue && peek() != Token::STRING) {
On 2014/02/06 09:38:05, ulan wrote:
> We discussed offline that the loop can be simplified. Now I got why mode
> detection is in a loop. This is probably because we can have multiple
> directives.
> 

Yep. I'll leave it like this for this CL. When merging
PreParser::ParseSourceElements and Parser::ParseSourceElements, I'll need
another round of unification for actually comparing the directive string to
something.

https://codereview.chromium.org/150103004/diff/30001/src/preparser.cc#newcode476
src/preparser.cc:476: if (peek() == Token::COLON && starts_with_idenfifier &&
expr.IsIdentifier()) {
On 2014/02/06 09:38:05, ulan wrote:
> Typo: starts_with_idenTifier.
> 
> Doesn't  starts_with_identifier imply expr.IsIdentifier()?

Fixed the typo.

No, it doesn't imply, because we can have expressions like "foo + bar" which
start with an identifier but the expression is not an identifier.

[marja, 2014-02-06 10:28:26]

https://codereview.chromium.org/150103004/diff/30001/src/preparser.cc
File src/preparser.cc (right):

https://codereview.chromium.org/150103004/diff/30001/src/preparser.cc#newcode476
src/preparser.cc:476: if (peek() == Token::COLON && starts_with_idenfifier &&
expr.IsIdentifier()) {
On 2014/02/06 10:27:53, marja wrote:
> On 2014/02/06 09:38:05, ulan wrote:
> > Typo: starts_with_idenTifier.
> > 
> > Doesn't  starts_with_identifier imply expr.IsIdentifier()?
> 
> Fixed the typo.
> 
> No, it doesn't imply, because we can have expressions like "foo + bar" which
> start with an identifier but the expression is not an identifier.

-> I'll add a comment about this...

[marja, 2014-02-06 10:30:11]

Committed patchset #4 manually as r19140 (presubmit successful).