Bug 705046 - Disable the chunks of test_html5_tree_construction_part2.html which touch plugins and thus expose our brokenness on 10.8

--HG--
extra : rebase_source : 566332fd749935688e36c8ed8f2b54d9b8f05ec4

parser/htmlparser/tests/mochitest/test_html5_tree_construction_part2.html

@@ -37,7 +37,8 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=366936
                          "webkit01.dat",
                          "webkit02.dat"];
     const isOSXLion = navigator.userAgent.indexOf("Mac OS X 10.7") != -1;
-    if (!isOSXLion) {
+    const isOSXMtnLion = navigator.userAgent.indexOf("Mac OS X 10.8") != -1;
+    if (!isOSXLion && !isOSXMtnLion) {
       parserDatFiles.push("tests19.dat");
       parserDatFiles.push("tests7.dat");
     }