Some applications truncates the last closing parenthesis in perf dashboard URL

Some applications truncates the last closing parenthesis in perf dashboard URL
https://bugs.webkit.org/show_bug.cgi?id=157976

Reviewed by Tim Horton.

Unfortunately, different applications use different heuristics to determine the end of each URL. Two trailing
parentheses, for example, is just fine in Radar as well as Apple Mail if the URL is short enough. Using other
characters such as ] and } wouldn't work either because they would be %-escaped. At that point, we might as well
as %-escape everything.

Work around the bug by parsing the URL as if it had one extra ')' if the parsing had failed. Also shorten the charts
page's URL by avoid emitting "-null" for each pane when the pane doesn't have a currently selected point or selection.
This improves the odds of the entire URL being recognized by various applications.

We could, in theory, implement some sort of a URL shorter but that can wait until when we support real user accounts.

* public/v3/pages/chart-pane.js:
(ChartPane.prototype.serializeState): Don't serialize the selection or the current point if nothing is selected.
* public/v3/pages/page-router.js:
(PageRouter.prototype._deserializeHashQueryValue): Try parsing the value again with one extra ] at the end if
the JSON parsing had failed.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@201307 268f45cc-cd09-0410-ab3c-d52691b4dbfc