Backed out changeset 9f9e83390b46 (debugging patch for bug 991600) because the problem with the test was identified
Bug 993772 - Stop serializing principals along with scripts. r=mrbkap

The principal of a script is determined by the compartment these days, so this
field is useless.
Bug 993772 - Introduce a singleton compilation scope. r=mrbkap
Bug 993772 - Switch to the singleton compilation scope for XBL compilation. r=mrbkap
Bug 993772 - Remove nsXBLDocGlobalObject. r=mrbkap
Bug 993772 - Switch to the singleton compilation scope for XUL prototype compilation. r=mrbkap
Bug 993772 - Remove nsXULPDGlobalObject. r=mrbkap
Back out bug 988653 (since it depends on bug 613659)
Merge backout
Back out bug 613659 (for regression bug 998792)

--HG--
rename : layout/reftests/backgrounds/background-size-slice.html => layout/reftests/backgrounds/background-size-continuous.html
rename : layout/reftests/backgrounds/background-size-cover-slice.html => layout/reftests/backgrounds/background-size-cover-continuous.html
rename : layout/reftests/backgrounds/background-size-cover-clone.html => layout/reftests/backgrounds/background-size-cover-each-box.html
rename : layout/reftests/backgrounds/background-size-clone.html => layout/reftests/backgrounds/background-size-each-box.html
Merge backout
Merge m-i to m-c
Merge f-t to m-c