Since we already have cache on V8 side we can introduce caching on inspector side. It will decrease memory consumption and reduce time which we spend for collecting stacks. See [1] for details.

[1] https://docs.google.com/a/google.com/document/d/13H1Pn6dekcwqlaYP26CfyyYGuL-U9LtUPWmt3TIpOag/edit?usp=sharing

BUG=v8:6189
R=dgozman@chromium.org,yangguo@chromium.org

Review-Url: https://codereview.chromium.org/2825903002
Cr-Commit-Position: refs/heads/master@{#44753}