This changes the compiler to be more aggressive about lazy compilation
of closures with non-trivial outer context. Compilation can only be
triggered with a valid outer context now. One exception is the debugger,
which can request compilation of arbitrary shared code, but it ensures
to trigger compilation only at points where no context is needed.

This relands r11782, r11783, r11790 and a minor fix.

R=ulan@chromium.org
TEST=mjsunit/debug-script-breakpoints-nested

Review URL: https://chromiumcodereview.appspot.com/10543141

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11866 ce2b1a6d-e550-0410-aec6-3dcde31c8c00