Fix for #1575 where postcss was raising an exception
* adapt the entire CSS as a whole in one pass with postcss, rather than adapting each split part separately
* break up the postcss output again and assign to individual text nodes (kind of inverse of splitCssText at record side)
* impose an upper bound of 30 iterations on the substring searches to preempt possible pathological behavior
* add tests to demonstrate the scenario and prevent regression
More technical details:
* Fix algorithm; checks against `ix_end` within loop were incorrect when `ix_start` was bigger than zero.
* Fix that length check against wrong array was causing 'should record style mutations with multiple child nodes and replay them correctly' test to fail.
Note on last point: I haven't looked into things more deeply than that the test was complaining about missing .length after `replayer.pause(1000);`
a6893f73ab