Make the implementation of Formatter %e more similar to %f.

Also comment the code that turns 'E' into 'e' in %e. I tried doing this in
native code but it crufts the implementation and slightly slows the path we
care about (%f) for the benefit of the one we don't (%e).

I have optimized %e (without a precision) in the same way that I did with %f.

Bug: 2934304
Change-Id: I3c99be2157f4448c1b290d5578eeb6fc14965c59
1 file changed