Kill WTF::DecimalNumber class

Kill WTF::DecimalNumber class

Kill WTF::DecimalNumber class and use the Decimal class from platform/ instead.
There is little sense in having 2 different classes to do the same thing. This
makes the code a bit more consistent and also reduces the release binary size
by ~15Kb.

R=eseidel@chromium.org, abarth@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=174260

[Inactive, 2014-05-14 01:19:32]

I noticed that we have 2 classes to do the same thing:
- wtf/DecimalNumber.h
- platform/Decimal.h

I am proposing to harmonize and keep only 1 of them. Let me know what you think.

[tkent, 2014-05-19 00:18:08]

lgtm.

We haven't evaluated the performance of Decimal class.  This might cause
performance issues.

[tkent, 2014-05-19 00:18:14]

The CQ bit was checked by tkent@chromium.org

[commit-bot: I haz the power, 2014-05-19 00:18:36]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/ch.dumez@samsung.com/285643006/80001

[commit-bot: I haz the power, 2014-05-19 10:08:04]

Change committed as 174260