Merge pull request #506 from ochameau/bug/776860-fix-http-pref

fix Bug 776860: test-request.testInvalidJSON (exception) r=@gozala
Merge pull request #492 from erikvold/bug682681-tab-title

fix Bug 682681 tab.title should never be empty r=@gozala
Fixes for can't redefine non-configurable property exceptions.
Merge pull request #471 from ochameau/bug/766917-fix-widget-test

Bug 766917: Fix application of panel style to its document. r=@gozala(cherry picked from commit cd13decd45fe6c6c409f8408281e192d76b28bba)
Merge pull request #480 from ochameau/bug/769483-nsIDOMParser-exception

Bug 769483: Fix exception when using data:URI documents instanciated with nsIDOMParser. r=@gozala
Throw an explicit error message to ease repack of addon using SDK <=1.5 and xpcom module.
removing some unnecessary code in api-utils/windows/observer
Merge release back to stabilization
Merge pull request #513 from erikvold/minor-winobs-chg

removing some unnecessary code in api-utils/windows/observer r=@gozala
Modified Unit Test to check the `contentType` after reload
Merge remote-tracking branch 'upstream/master' into tab.contentType/Bug775606

Conflicts:
	packages/api-utils/lib/tabs/tab.js
Merge branch 'master' into 734201
Merge pull request #501 from wbamberg/754111

Fix bug 754111 - Documentation for writing tests should recommend commonjs style
Merge branch 'master' into 734201
update text referring to 'main.js'
Fix bug 778213 by changing the expected headers
Fix review comments; fix a CSS problem
fix merge conflicts
fix up code samples
Merge pull request #489 from wbamberg/734201

Fix bug 734201 - Tutorial for interaction with page scripts through page mod.