Upgrade a TextIterator ASSERT to a RELEASE_ASSERT as a defensive measure.

BUG=156930,177197
R=inferno@chromium.org

Review URL: https://codereview.chromium.org/15057010

git-svn-id: svn://svn.chromium.org/blink/trunk@150123 bbb929c8-8fbe-4397-9dbb-9b2b20218538
void TextIterator::representNodeOffsetZero()
{
    
    if (shouldEmitTabBeforeNode(m_node)) {
        if (shouldRepresentNodeOffsetZero())
            emitCharacter('\t', m_node->parentNode(), m_node, 0, 0);
    } else if (shouldEmitNewlineBeforeNode(m_node)) {
        if (shouldRepresentNodeOffsetZero())
            emitCharacter('\n', m_node->parentNode(), m_node, 0, 0);
    } else if (shouldEmitSpaceBeforeAndAfterNode(m_node)) {
        if (shouldRepresentNodeOffsetZero())
            emitCharacter(' ', m_node->parentNode(), m_node, 0, 0);
    }
}

void TextIterator::representNodeOffsetZero()
{
    
    if (shouldEmitTabBeforeNode(m_node)) {
        if (shouldRepresentNodeOffsetZero())
            emitCharacter('\t', m_node->parentNode(), m_node, 0, 0);
    } else if (shouldEmitNewlineBeforeNode(m_node)) {
        if (shouldRepresentNodeOffsetZero())
            emitCharacter('\n', m_node->parentNode(), m_node, 0, 0);
    } else if (shouldEmitSpaceBeforeAndAfterNode(m_node)) {
        if (shouldRepresentNodeOffsetZero())
            emitCharacter(' ', m_node->parentNode(), m_node, 0, 0);
    }
}
