The root of problem is the fact that we don't track the position of 'this' statement but use them when visit compare statement.
As a result we have -1 as the position of left expression and the resulting relative position is negative and doesn't fit into BitField.

BUG=452067
TEST=test-cpu-profiler/SourceLocation
LOG=n

Review URL: https://codereview.chromium.org/940593002

Cr-Commit-Position: refs/heads/master@{#26741}