Inlining heuristics in Turbofan used ast node count. Bytecode size
is a better approximation of the size of the graph than the
ast node count. This cl changes the heuristics to use the bytecode
size instead. Also removing the ast_node_count filed in the shared
function info. It was used only for the inlining heuristics.

Also removed the max_inlined_source_size flag which is no longer used.

Bug: 
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I8a2d2509c8e8d2779b33b817bb217de203d54ec3
Reviewed-on: https://chromium-review.googlesource.com/570055
Commit-Queue: Mythri Alle <mythria@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46771}