Remove symbol preparse data altogether.

Remove symbol preparse data altogether.

Removing it seems to be a clear win on mobile: producing symbol data makes cold
parsing 20-30% slower, and having symbol data doesn't make warm parsing any
faster.

Notes:
- V8 used to produce symbol data, but because of a bug, it was never used until
recently. (See fix https://codereview.chromium.org/172753002 which takes the
symbol data into use again.)
- On desktop, warm parsing is faster if we have symbol data, and producing it
during cold parsing doesn't make parsing substantially slower. However, this
doesn't seem to be the case on mobile.
- The preparse data (cached data) will now contain only the positions of the
lazy functions.

BUG=
R=dcarney@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=21146

[marja, 2014-05-05 13:28:11]

dcarney@, ptal, jochen@, fyi.

Let's stop the symbol data madness now!

Some measurements on mobile. These were done with parser shell.

Data set 1 (20 M, contains some lazy functions).

Baseline cold: ~8400 ms
Baseline warm: ~6000 ms

Without symbol data cold: ~7000 ms
Without symbol data warm: ~5800 ms (*)

(*) This is less than cold, because we can skip over lazy functions.

Data set 2 (2.7 M, artificially made non-lazy to make it contain lots of
symbols):

Baseline cold: ~ 1700 ms
Baseline warm: ~ 1300 ms

Without symbol data cold: ~1300 ms
Without symbol data warm: ~1300 ms (*)

This is same than the cold time, because there are no lazy functions we can skip
over.

[dcarney, 2014-05-05 13:31:44]

lgtm

[dcarney, 2014-05-05 13:31:45]

lgtm

lgtm

[marja, 2014-05-05 14:55:22]

Committed patchset #3 manually as r21146 (presubmit successful).