First, retrieve current theme only in cases when it already has been
provided in the context. That should prevent missing 'THEME' errors
when post_compress signal is being processed, for example inside
_stylesheets.html which does not provide THEME var into the rendering
context.
Second, under certain circumstances, offline compression was producing
a different hash for compressed angular templates than runtime
template renderer was expecting. Make the combined template with all
angular templates be a deterministic - convert it from a dictionary to
a list of key-value tuples. Various order of dictionary entries in
offline and online compress phases seemed to produce 'missing compress
hash key' error.
Closed-Bug: #1603307
Change-Id: Idb48c3f68da43bba33033a71e6d69bdc112736de
9445d15cd1