DevTools: [FlameChart] replace popover with text on canvas.
DevTools: [FlameChart] replace popover with text on canvas.

There is a flakiness when we moves cursor over the flame chart.
So we decided to replace popover with text on canvas in left top corner of it.

BUG=235069
TEST=none
R= pfeldman@chromium.org, yurys@chromium.org

Review URL: https://codereview.chromium.org/14054014

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@149082 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs