Re-implement exception handler inlining in the new optimizer

[lrytz]

The old optimizer inlined exception handlers if a throw throws an exception that is caught in the same method. According to @VladUreche, this is mainly to support two use-cases:

• breakable { ...; break; ... }
• return statements

https://github.com/scala/scala/blob/2.11.x/src/compiler/scala/tools/nsc/backend/opt/InlineExceptionHandlers.scala

[VladUreche]

:+1: to ASM-level inline exception handlers

[lrytz]

Existing test currently in pending: https://github.com/scala/scala/blob/93fa559f62637fc3a49d7b961a1d07cf843b0e6b/test/pending/run/inline-ex-handlers.scala