[WebAssembly] Fix bugs in WebAssemblyLowerEmscriptenExceptions pass

* Delete extra '_' prefixes from JS library function names. fixImports()
  function in JS glue code deals with this for wasm.
* Change command-line option names in order to be consistent with
  asm.js.
* Add missing lowering code for llvm.eh.typeid.for intrinsics
* Delete commas in mangled function names
* Fix a function argument attributes bug. Because we add the pointer to
  the original callee as the first argument of invoke wrapper, all
  argument attribute indices have to be incremented by one.

Patch by Heejin Ahn

Differential Revision: https://reviews.llvm.org/D23258

llvm-svn: 278081