These wrappers are not natively understood by
ts2dart. Removing them will improve Dart2JS
compilation due to fewer megamorphic calls to List
functions.
It also makes Angular code more succinct and
improves type safety in Angular due to better type
inference of the Array component type.
This change exposed several bugs in Angular.
Largetable benchmark with `interpolationAttr` and 200 rows / 20 columns:
Time for destroy/create pair dropped from about 1260ms to about 150ms.
Related to #2298, but does not really fix it as we are still slow
if people are using `<content>`.
Closes#2297