Add duplicate parameter detection to preparser.

Add duplicate parameter detection to preparser.
Add tests for duplicate properties of object initialisers to preparser.

TEST=preparser

Committed: http://code.google.com/p/v8/source/detail?r=8517

[Lasse Reichstein, 2011-06-15 15:26:17]

We might want to hold this back until we do proper string->double->string
conversion for numeric object properties, otherwise we can get false negatives.

[Mads Ager (chromium), 2011-06-16 06:48:56]

http://codereview.chromium.org/7168016/diff/4008/src/preparser.cc
File src/preparser.cc (right):

http://codereview.chromium.org/7168016/diff/4008/src/preparser.cc#newcode1099
src/preparser.cc:1099: int intersect = old_value & type;
And this is what that comment on the enum should say. You are using it to check
for overlapping properties with special treatment for a getter and a setter with
the same name.

http://codereview.chromium.org/7168016/diff/4008/src/preparser.cc#newcode1101
src/preparser.cc:1101: if ((intersect & kValueFlag) != 0) {
Maybe have methods for these bit operations?

BothDataProperties(type1, type2)
DataAndAccessorProperty(type1, type2)

http://codereview.chromium.org/7168016/diff/4008/src/preparser.cc#newcode1616
src/preparser.cc:1616: bool is_ascii) {
indentation

http://codereview.chromium.org/7168016/diff/4008/src/preparser.h
File src/preparser.h (right):

http://codereview.chromium.org/7168016/diff/4008/src/preparser.h#newcode56
src/preparser.h:56: ~DuplicateFinder() {
Could you add a line between constructor and destructor?

http://codereview.chromium.org/7168016/diff/4008/src/preparser.h#newcode118
src/preparser.h:118: enum PropertyType {
Please add a comment about the format here. I don't understand why value
property is 7 instead of 4?

http://codereview.chromium.org/7168016/diff/4008/test/preparser/testcfg.py
File test/preparser/testcfg.py (right):

http://codereview.chromium.org/7168016/diff/4008/test/preparser/testcfg.py#ne...
test/preparser/testcfg.py:146: executable, current_path, mode)
indentation