Make safari only break on fractions

Summary: Also, make errors on the initial parse not prevent further
parses.

Auditors: alpert

katex.js

@@ -86,6 +86,10 @@ var buildGroup = function(style, color, group, prev) {
     } else if (group.type === "close") {
         return makeSpan("mclose" + color, [textit(group.value)]);
     } else if (group.type === "frac") {
+        if (utils.isSafari) {
+            throw new ParseError("KaTeX fractions don't work in Safari");
+        }
+
         var fstyle = style;
         if (group.value.size === "dfrac") {
             fstyle = Style.DISPLAY;
@@ -244,10 +248,6 @@ var clearNode = function(node) {
 };
 
 var process = function(toParse, baseNode) {
-    if (utils.isSafari) {
-        throw new ParseError("KaTeX doesn't work on Safari");
-    }
-
     clearNode(baseNode);
     var tree = parseTree(toParse);
 

static/main.js

@@ -2,14 +2,14 @@ window.onload = function() {
     var input = document.getElementById("input");
     var math = document.getElementById("math");
 
-    reprocess();
-
     if ("oninput" in input) {
         input.addEventListener("input", reprocess, false);
     } else {
         input.attachEvent("onkeyup", reprocess);
     }
 
+    reprocess();
+
     function reprocess() {
         katex.process(input.value, math);
     }