Apply behaviour change fix from upstream for previous XPath change.

BUG=58731
TEST=NONE

Review URL: http://codereview.chromium.org/4027006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@63572 0039d316-1c4b-4281-b951-d872f2087c98
xmlXPathInit(void) {
    if (xmlXPathInitialized) return;

    xmlXPathPINF = trio_pinf();
    xmlXPathNINF = trio_ninf();
    xmlXPathNAN = trio_nan();
    xmlXPathNZERO = trio_nzero();

    xmlXPathInitialized = 1;
}

xmlXPathInit(void) {
    if (xmlXPathInitialized) return;

    xmlXPathPINF = trio_pinf();
    xmlXPathNINF = trio_ninf();
    xmlXPathNAN = trio_nan();
    xmlXPathNZERO = trio_nzero();

    xmlXPathInitialized = 1;
}
