Bug 976938 - Add a way to identify the Xray parent (if any) of a given function. r=bz
Bug 977340 - Use an AutoJSContext when clearing modules. r=gabor
Bug 977340 - Do some gymnastics to avoid tripping cx assertions when cloning exceptions from evalInWindow calls. r=gabor
Bug 977340 - Clean up cx usage in Promises. r=bz

None of these are hazards, because we already make sure to push the JSContext
in the cases where we do anything meaningful in JSAPI. But the current setup
trips the new assertions, and is ugly to boot. Let's fix it.
Bug 977340 - Assert during compartment checking that we're using the stack-top cx. r=luke,gabor
Bug 916644 - Disable invoking WebIDL constructors without |new| unless you have the system principal. r=bz