Merge 122552 - REGRESSION(r119948): [Forms] Spin button Up/Down actions make value to zero for inpu…

Merge 122552 - REGRESSION(r119948): [Forms] Spin button Up/Down actions make value to zero for input type "number" when step mismatched
https://bugs.webkit.org/show_bug.cgi?id=91197

Reviewed by Kent Tamura.

Source/WebCore:

This patch fixes implementation of Decimal::ceiling() and floor().
They return wrong value for small fractional numbers.

The bug is occurred when:
  - Step-able input type, e.g. number, date, datetime, and so on.
  - Current value is step mismatched
  - Current value is smaller than step
  - Step up/down by spin button
because spin button up/down actions are implemented in InputType::setpUpFromRenderer
which calls Decimal::ceiling() and floor() for step mismatched case.

Tests: fast/forms/number/number-stepup-stepdown-from-renderer.html: Added test cases
       WebKit/chromium/tests/DecimalTest.cpp: Added test cases

* platform/Decimal.cpp:
(WebCore::Decimal::ceiling): Changed to return 1 for positive small fractional number.
(WebCore::Decimal::floor): Changed to return -1 for negative small fractional number.

Source/WebKit/chromium:

This patch adds test cases for Decimal::ceiling() and floor() of
positive/negative small fractional numbers.

* tests/DecimalTest.cpp:
(TEST_F):

LayoutTests:

This patch adds new test cases.

* fast/forms/number/number-stepup-stepdown-from-renderer-expected.txt: Updated for new test cases.
* fast/forms/number/number-stepup-stepdown-from-renderer.html: Added new test cases.

TBR=yosin@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=122853