Make HTMLCanvasElement::convertLogicalToDevice() clamp float to integer.

Make HTMLCanvasElement::convertLogicalToDevice() clamp float to integer.

convertLogicalToDevice() has a potential issue to return a falsely negative
value due to integer precison.

[dshwang, 2013-11-19 11:04:04]

expandedIntSize() implementation is as follows:

inline IntSize expandedIntSize(const FloatSize& p)
{
    return IntSize(clampToInteger(ceilf(p.width())),
clampToInteger(ceilf(p.height())));
}


I found this issue when testing https://codereview.chromium.org/44253005/
for example,
let width 2147483610 and scale 1.0

unfortunately, 2147483610 * 1.0 = 2147483648.0 due to float precision.
and then (int)2147483648 = -2147483648


expandedIntSize() is our friend.

[Stephen White, 2013-11-19 16:59:40]

On 2013/11/19 11:04:04, dshwang wrote:
> expandedIntSize() implementation is as follows:
> 
> inline IntSize expandedIntSize(const FloatSize& p)
> {
>     return IntSize(clampToInteger(ceilf(p.width())),
> clampToInteger(ceilf(p.height())));
> }
> 
> 
> I found this issue when testing https://codereview.chromium.org/44253005/
> for example,
> let width 2147483610 and scale 1.0
> 
> unfortunately, 2147483610 * 1.0 = 2147483648.0 due to float precision.
> and then (int)2147483648 = -2147483648
> 
> 
> expandedIntSize() is our friend.

Could you fold this change into the other one, so it is tested there?

[dshwang, 2013-11-19 17:15:08]

On 2013/11/19 16:59:40, Stephen White wrote:
> Could you fold this change into the other one, so it is tested there?

Yes, I updated https://codereview.chromium.org/44253005/ to merge this CL with
it.