A Linux system running over JavaScript

Just a follow-up.

http://codereview.chromium.org/7037023

It's theoretically addressing v8 issue 1394, but in fact it's more about Chromium issue 82828. The problem of v12/13 was just briefly mentioned in "PC emulator is about 2 times slower using V8 than Jaeger Monkey" report and did not have deserving separate issue in v8 project.

> Fix bug in optimized compiler's switch-statement.
>
> In the case where the default-clause occurs as the first clause, the case-blocks were not wired up correctly.

So it was a matter of extracting non-NULL check equivalently from if block into inner if. That shouldn't be really needed in obtaining correct behavior though...

Speed deficiency (when compared to Fx) remains for the time being.