Fix #14101: $().data() should be undefined, not null

- Backported 30eee925dbc9f8d465ccf064f48c24061ffdc378 for 1.x
Ref fb2e0a0c: Synchronize unit tests with master
Fix #14074: element id="nodeName". Close gh-1389.
Ref c66a5e70: Synchronize unit tests with master
Fix #14422 and add more thorough check for CSP violations

Close gh-1413
Fix #12757 - use jscs to check the style guide

Cherry picked from ab63e568f50b5b9823490eda9c184e48cc6440c4 commit
Fix some code style inconsistencies
Add load-grunt-tasks package dependency

Cherry picked from abfa210adfaee28e2496d7749d675d157d8e6c9d commit
Add "keywords" to bower.json

Cherry picked from 0bb4090c2c77746ae3976bcce52ea3f58a056604 commit
Use full version of jQuery 1.9.1

Had some weird failures in IE with xhr build of 1.9.1.
Cherry picked from 626cbde7f8267e2463cef85d84f9f0172f1c7cb9 commit
Don't execute focus tests in Firefox

Cherry picked from 45be91e3981164e076a71de31f0b8a972a4bf104 commit
Check Gruntfile and tasks for code style

Cherry picked from 85d4c0133b5369b54bc9c4250989214bb2d45700 commit
Merge branches '1.x-master' and '1.x-master' of github.com:jquery/jquery into 1.x-master
Ref 705216d: Synchronize ajax/xhr.js with master
Remove old try...catch for old FF
Remove workarounds for the uglify task mishandling banners when used with source maps. (cherry-picked from d0fadbba9f1dbe2ee009be6586fbdf3cda4eff98)

The issue was fixed in grunt-contrib-uglify:
https://github.com/gruntjs/grunt-contrib-uglify/issues/22
No ticket. Restore some parsing tests in core. (cherry-picked from 650f325d8e5e9092cd8ca7c1a7ab62c4bba582cf)
Grunt: put .sizecache.json in build/, not dist/. (see 6095be1260c5c0e7dfe88380501188d4c50975eb)
Fix #14415. Remove the source map comment in the release script. Close gh-1424. (cherry-picked from 562145e887cc42ce8c9c9cd2c6e946ff01e6731d)
No ticket. Remove the pre-uglify task form build/tasks/build.js. Fix custom builds. (cherry-picked from 7d5a12376d18e0ec70241e653721ce9977123d34)