swift234

[stdlib] Make a bunch of standard library functions compile faster.

The targeted functions all take over a second to type-check with my debug
compiler (found using -debug-time-function-bodies). The top two---the two
replaceRange implementations---took about a minute each; this change
knocks them down to 30-40s.

All of this is just breaking expressions apart, and the expressions aren't
even that complicated. I'm concerned that we have a serious performance
regression around the use of lazy(), and I've filed rdar://problem/20875936
so we can look into it. The test change is particularly concerning; there's
a ridiculous difference between 'lazy(...).reverse()' and
'lazy(...).reverse().reverse()'.

No intended functionality change.

Swift SVN r28325