Expose ID of relevant page in JS variables

Bug: 53774
Change-Id: I06cd037804daba59e4f42e3be5f2883a82fcaa27
Omit 'window.' when accessing browsing location

The location object is a global, just like document.

Using it via 'window' needlessly adds complexity and, for example,
makes it harder to catch typos in static analysis.

Also standardise on location.href in place of the many different
variants, like:

 location =
 location.href =
 location.assign() =

And each with 'window', 'document' and without host object.

Change-Id: I77510294d8b5bd4b8a1b08e06817762a7839d43d
Merge "Expose ID of relevant page in JS variables"
Merge "Omit 'window.' when accessing browsing location"