Fix #811: Remove deserialization hacks.
Fix #1040: Manually put @RawJSType on js.UndefOr.
Fix #863: Cleanup Javalib

This commit comments all methods in the Javalib which throw a not
implemented exception. This allows the linker to detect usage of such
a method, rather than having the program fail at runtime.
Merge pull request #1077 from sjrd/remove-deser-hacks

Fix #811: Remove deserialization hacks.
Fix #1039: Change JSDelete to contain a JS{Dot,Bracket}Select.

Note: JSDelete(JSDotSelect(_, _)) is completely untested. I do
not know what to do about it.
Merge pull request #1076 from sjrd/rawjstype-undefor

Fix #1040: Manually put @RawJSType on js.UndefOr.
Merge pull request #1079 from sjrd/jsdelete-dot-bracket

Fix #1039: Change JSDelete to contain a JS{Dot,Bracket}Select.
Merge pull request #1078 from gzm0/cleanup-javalib

Fix #863: Cleanup Javalib
Fix #1047: Remove Object.getClass__jl_Class from IR.
Fix #1046: Remove identityHashCode0.
Merge pull request #1080 from sjrd/remove-bin-compat-in-ir

Remove binary compat hacks in IR