Introduce a flag --max_inlined_nodes_small (defaults to 10), which gives
the upper limit of AST nodes for a function to be considered "small" by
the inlining heuristic. These functions will always be inlined
immediately, independent of the budget.

R=jarin@chromium.org
BUG=v8:6395,v8:6278,v8:6344,v8:6394

Review-Url: https://codereview.chromium.org/2883853002
Cr-Commit-Position: refs/heads/master@{#45291}