Roll libxslt to 891681e3e948f31732229f53cb6db7215f740fc7

BUG=583156,583171

Review URL: https://codereview.chromium.org/1853083002

Cr-Commit-Position: refs/heads/master@{#385338}
xsltFreeCtxtExts(xsltTransformContextPtr ctxt)
{
    if (ctxt->extElements != NULL)
        xmlHashFree(ctxt->extElements, NULL);
    if (ctxt->extFunctions != NULL)
        xmlHashFree(ctxt->extFunctions, NULL);
}

xsltFreeCtxtExts(xsltTransformContextPtr ctxt)
{
    if (ctxt->extElements != NULL)
        xmlHashFree(ctxt->extElements, NULL);
    if (ctxt->extFunctions != NULL)
        xmlHashFree(ctxt->extFunctions, NULL);
}
