FlameChart: show deoptimize reason text for the selected function and draw bold text on the bar.

V8 could provide deoptimization info for functions and we can show it.
The simplest solution is to show it on the FlameChart.
If a function bar has deoptReason then:
a) print bar text with bold font;
b) we print it in the text box when corresponding bar is selected.

tip: for reducing the number of calls of context.font method we cache
the font state and change the font only if necessary. Otherwise we will have
performance degradation.

Should be landed only after v8 patch https://codereview.chromium.org/23817003/ and v8 roll.

BUG=285050
R=alph@chromium.org, vsevik@chromium.org

Review URL: https://codereview.chromium.org/23946002

git-svn-id: svn://svn.chromium.org/blink/trunk@157518 bbb929c8-8fbe-4397-9dbb-9b2b20218538