DevTools: Refactor Profiler domain interface

Flatten nodes into an array.

Review-Url: https://codereview.chromium.org/2244783004
Cr-Original-Commit-Position: refs/heads/master@{#412613}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 3b17e107b6801bc18861154e707dfa57ba23a909
2 files changed