Stop interpreter from accessing code items of compiled code.

The ArtInterpreterToCompiledCodeBridge accesses the code item in a
number of places to handle argument marshalling. However, the code item
of a compiled method should have no need to be accessed by the runtime
at all, since the code has been compiled. By removing these accesses,
there is a drop in the memory footprint of the dex file, since these
code items remain untouched by the runtime.

Bug: 35800981
Test: mm test-art-host
Change-Id: Ib7d29c17e80b1690aa819d083f5b12739492ebd6