Fix var declarations inside for loops at the top level

Var declarations were always rewritten to assignment statements, however, in
a for loop, the initializer can be either a var decl or an expression but not
an arbitrary statement.

This change rewrites a var declaration to a statement iff it occurs outside
a for-loop (according to the SpiderMonkey parser api)

@5234

[MarkM, 2013-01-27 18:53:07]

https://codereview.appspot.com/7230046/diff/1/src/com/google/caja/ses/mitigat...
File src/com/google/caja/ses/mitigateGotchas.js (right):

https://codereview.appspot.com/7230046/diff/1/src/com/google/caja/ses/mitigat...
src/com/google/caja/ses/mitigateGotchas.js:58: node.type == 'ForOfStatement' ||
I'm surprised this has ForOfStatement. That's introduced by ES6. Does this
parser support any other ES6 features? (If so, that may have other implications.
Haven't thought about this yet.)

https://codereview.appspot.com/7230046/diff/1/src/com/google/caja/ses/mitigat...
src/com/google/caja/ses/mitigateGotchas.js:88: * global.x = global.x, global.y =
2, global.z = global.z
Please expand doc-comment to cover the "for" rewrite.

https://codereview.appspot.com/7230046/diff/1/src/com/google/caja/ses/mitigat...
src/com/google/caja/ses/mitigateGotchas.js:201: var parent = path[path.length -
1];
Nice. I like the consolidation of the path mechanics.

[Jasvir, 2013-01-27 19:52:52]

Var declarations were always rewritten to assignment statements, however, in
a for loop, the initializer can be either a var decl or an expression but not
an arbitrary statement.

This change rewrites a var declaration to a statement iff it occurs outside
a for-loop (according to the SpiderMonkey parser api)

[Jasvir Nagra, 2013-01-27 19:53:09]

https://codereview.appspot.com/7230046/diff/1/src/com/google/caja/ses/mitigat...
File src/com/google/caja/ses/mitigateGotchas.js (right):

https://codereview.appspot.com/7230046/diff/1/src/com/google/caja/ses/mitigat...
src/com/google/caja/ses/mitigateGotchas.js:58: node.type == 'ForOfStatement' ||
Actually the parser does not recognize ForOfStatements.  I took the list of
possible places where a VarDecl could appear from the SpiderMonkey parser api. 
Removed for now.

https://codereview.appspot.com/7230046/diff/1/src/com/google/caja/ses/mitigat...
src/com/google/caja/ses/mitigateGotchas.js:88: * global.x = global.x, global.y =
2, global.z = global.z
On 2013/01/27 18:53:07, MarkM wrote:
> Please expand doc-comment to cover the "for" rewrite.

Done.

https://codereview.appspot.com/7230046/diff/1/src/com/google/caja/ses/mitigat...
src/com/google/caja/ses/mitigateGotchas.js:201: var parent = path[path.length -
1];
On 2013/01/27 18:53:07, MarkM wrote:
> Nice. I like the consolidation of the path mechanics.

Done.

[MarkM, 2013-01-27 20:50:24]

LGTM

[ihab.awad, 2013-01-28 05:30:30]

lgtm2