Now that function counts are based on dedicated call counters instead
of FeedbackVector::invocation_count, we can enable optimizations for
block coverage modes.

This significantly speeds up V8 with enabled coverage:

Before this CL, the web-tooling-benchmark regressed by 70% (block
count coverage vs. no coverage).  With this CL, the regression is
reduced to 40%.

Bug: v8:6000,v8:9148
Change-Id: I6bb538bd66f32f016c66c1d1996bce3b25958232
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1615241
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61582}