Added test case for github codeblock at start of string

src/showdown.js

@@ -910,12 +910,13 @@ var _DoGithubCodeBlocks = function(text) {
 			var language = m1;
 			var codeblock = m2;
 
+			console.log('codeblock', '|' + codeblock + '|');
 			codeblock = _EncodeCode(codeblock);
 			codeblock = _Detab(codeblock);
 			codeblock = codeblock.replace(/^\n+/g,""); // trim leading newlines
 			codeblock = codeblock.replace(/\n+$/g,""); // trim trailing whitespace
 
-			codeblock = "<pre><code" + (language ? " class=\"" + language : "\"") + ">" + codeblock + "\n</code></pre>";
+			codeblock = "<pre><code" + (language ? " class=\"" + language + '"' : "") + ">" + codeblock + "\n</code></pre>";
 
 			return hashBlock(codeblock);
 		}

test/cases/github-style-at-start.html

@@ -0,0 +1,7 @@
+
+<pre><code>function MyFunc(a) {
+    // ...
+}
+</code></pre>
+
+<p>That is some code!</p>

test/cases/github-style-at-start.md

@@ -0,0 +1,7 @@
+```
+function MyFunc(a) {
+    // ...
+}
+```
+
+That is some code!