Correctly format stack traces for errors with multiline messages

- Fixes #1526

src/core/StackTrace.js

@@ -1,13 +1,14 @@
 getJasmineRequireObj().StackTrace = function(j$) {
-  function StackTrace(rawTrace) {
-    var lines = rawTrace
+  function StackTrace(error) {
+    var lines = error.stack
       .split('\n')
       .filter(function(line) { return line !== ''; });
 
-    if (lines[0].match(/^Error/)) {
-      this.message = lines.shift();
-    } else {
-      this.message = undefined;
+    var extractResult = extractMessage(error.message, lines);
+
+    if (extractResult) {
+      this.message = extractResult.message;
+      lines = extractResult.remainder;
     }
 
     var parseResult = tryParseFrames(lines);
@@ -75,6 +76,34 @@ getJasmineRequireObj().StackTrace = function(j$) {
       }
     }
   }
+
+  function extractMessage(message, stackLines) {
+    var len = messagePrefixLength(message, stackLines);
+
+    if (len > 0) {
+      return {
+        message: stackLines.slice(0, len).join('\n'),
+        remainder: stackLines.slice(len)
+      };
+    }
+  }
+
+  function messagePrefixLength(message, stackLines) {
+    if (!stackLines[0].match(/^Error/)) {
+      return 0;
+    }
+
+    var messageLines = message.split('\n');
+    var i;
+
+    for (i = 1; i < messageLines.length; i++) {
+      if (messageLines[i] !== stackLines[i]) {
+        return 0;
+      }
+    }
+
+    return messageLines.length;
+  }
   
   return StackTrace;
 };