js_ast: Better escaping of strings in preparation for utf8 file encoding

js_ast: Better escaping of strings in preparation for utf8 file encoding

- Choose between single and double quotes to reduce number of escapes.
- With "uft8: true", leave most characters for the file encoding.
- LINE SEPARATOR and PAGE SEPARATOR must always be \uXXXX encoded.
- Unpaired surrogates must be encoded as \uXXXX.
- Use \xXX rather than \u00XX where possible.

R=sigmund@google.com

Committed: https://github.com/dart-lang/sdk/commit/dcf576a428eb95aa830fbee7a91006cddc6e8090

[sra1, 2015-12-12 01:25:51]

sra@google.com changed reviewers:
+ floitsch@google.com, sigmund@google.com

[Siggi Cherem (dart-lang), 2015-12-12 01:43:05]

lgtm!

https://codereview.chromium.org/1520033002/diff/1/pkg/js_ast/test/string_esca...
File pkg/js_ast/test/string_escape_test.dart (right):

https://codereview.chromium.org/1520033002/diff/1/pkg/js_ast/test/string_esca...
pkg/js_ast/test/string_escape_test.dart:130: check([0xD834, $A], [$DQ, 0xD834,
$A, $DQ]);  // Legacy escapedString broken.
nit: long line

[sra1, 2015-12-14 19:33:23]

Description was changed from

==========
js_ast: Better escaping of strings in preparation for utf8 file encoding

- Choose between single and double quotes to reduce number of escapes.
- With "uft8: true", leave most characters for the file encoding.
- LINE SEPARATOR and PAGE SEPARATOR must always be \uXXXX encoded.
- Unpaired surrogates must be encoded as \uXXXX.
- Use \xXX rather than \u00XX where possible.
==========

to

==========
js_ast: Better escaping of strings in preparation for utf8 file encoding

- Choose between single and double quotes to reduce number of escapes.
- With "uft8: true", leave most characters for the file encoding.
- LINE SEPARATOR and PAGE SEPARATOR must always be \uXXXX encoded.
- Unpaired surrogates must be encoded as \uXXXX.
- Use \xXX rather than \u00XX where possible.

R=sigmund@google.com

Committed:
https://github.com/dart-lang/sdk/commit/dcf576a428eb95aa830fbee7a91006cddc6e8090
==========

[sra1, 2015-12-14 19:33:24]

Committed patchset #2 (id:20001) manually as
dcf576a428eb95aa830fbee7a91006cddc6e8090 (presubmit successful).