Vector ICs: Clear the vector ic slots appropriately during debugging.

Vector ICs: Clear the vector ic slots appropriately during debugging.

When the debugger is active, a host of connected functions get an associated
DebugInfo structure, and their code is copied. The debugger uses the original
code to occasionally patch ICs with their initial value. Although IC learning
can occur, it's thrown away often, depending on the constellation of
breakpoints active or deactivating. Finally, feedback is discarded when the
debugger is turned off.

The type feedback vector needs to be brought into line with this behavior, so
now the debugger clears it's IC slots at appropriate bottlenecks in debug.cc.

R=yangguo@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1014373002

Cr-Commit-Position: refs/heads/master@{#27289}