Fix SES crashing if unsupported since r5359.

* StringMap.js assumed ses.es5ProblemReports existed; fixed.
* Added browser tests that initSES runs to completion even on
  (simulated) unsupported browsers.

@r5367

[ihab.awad, 2013-04-22 21:54:08]

lgtm

[kpreid2, 2013-04-23 00:00:25]

On 2013/04/22 21:54:08, ihab.awad wrote:
> lgtm

OK, waiting for approval from MarkM.

[MarkM, 2013-04-23 01:56:42]

LGTM

https://codereview.appspot.com/8913045/diff/1/src/com/google/caja/ses/StringM...
File src/com/google/caja/ses/StringMap.js (right):

https://codereview.appspot.com/8913045/diff/1/src/com/google/caja/ses/StringM...
src/com/google/caja/ses/StringMap.js:46: // Object.create(null) is broken; fall
back to ES3-style implementation
This comment is now stale. Please update.

[kpreid2, 2013-04-23 02:01:03]

https://codereview.appspot.com/8913045/diff/1/src/com/google/caja/ses/StringM...
File src/com/google/caja/ses/StringMap.js (right):

https://codereview.appspot.com/8913045/diff/1/src/com/google/caja/ses/StringM...
src/com/google/caja/ses/StringMap.js:46: // Object.create(null) is broken; fall
back to ES3-style implementation
On 2013/04/23 01:56:42, MarkM wrote:
> This comment is now stale. Please update.

How is it stale?

Longer version of what it is saying: In the presence of
FREEZING_BREAKS_PROTOTYPES, we reimplement Object.create using ES3-level
techniques, which cannot create a null [[Prototype]]. Therefore,
Object.create(null) throws, and StringMap must avoid using it.

[MarkM, 2013-04-23 02:09:21]

https://codereview.appspot.com/8913045/diff/1/src/com/google/caja/ses/StringM...
File src/com/google/caja/ses/StringMap.js (right):

https://codereview.appspot.com/8913045/diff/1/src/com/google/caja/ses/StringM...
src/com/google/caja/ses/StringMap.js:46: // Object.create(null) is broken; fall
back to ES3-style implementation
The code also covers the case where ses.es5ProblemReports doesn't exist. The
comment leaves this out of the explanation.

I don't feel strongly about this. If you feel strongly to the contrary, leave
this alone. LGTM anyway.