[CSS Shapes] inset complex calc() args vanish in serialized computed style

We didn't pass the style parameter when setting the width members of CSSBasicShapeInset,
which lead to a 'should never reach asserttion' in CSSPrimitiveValue::init. This patch
adds the missing parameters to the call sites.

This is a merge of http://trac.webkit.org/changeset/166894 by Zoltan Horvath <zoltan@webkit.org>.

BUG=350139

Review URL: https://codereview.chromium.org/228903002

git-svn-id: svn://svn.chromium.org/blink/trunk@171082 bbb929c8-8fbe-4397-9dbb-9b2b20218538