Set Attr.ownerDocument in Element#setAttributeNode()

Attr objects can move across documents by setAttributeNode().
So It needs to reset ownerDocument through TreeScopeAdoptr::adoptIfNeeded().

BUG=248950
TEST=set-attribute-node-from-iframe.html

Review URL: https://chromiumcodereview.appspot.com/17583003

git-svn-id: svn://svn.chromium.org/blink/trunk@152938 bbb929c8-8fbe-4397-9dbb-9b2b20218538
static inline bool classStringHasClassName(const AtomicString& newClassString)
{
    unsigned length = newClassString.length();

    if (!length)
        return false;

    if (newClassString.is8Bit())
        return classStringHasClassName(newClassString.characters8(), length);
    return classStringHasClassName(newClassString.characters16(), length);
}

static inline bool classStringHasClassName(const AtomicString& newClassString)
{
    unsigned length = newClassString.length();

    if (!length)
        return false;

    if (newClassString.is8Bit())
        return classStringHasClassName(newClassString.characters8(), length);
    return classStringHasClassName(newClassString.characters16(), length);
}
