Fix multi-line assertion messages in test runner

This commit prevents multi-line error messages from being
truncated in the local test runner ('tests/run_from_console.js').

tests/run_from_console.js

@@ -250,6 +250,24 @@ if (!program.outputHtml && !program.generateHtml) {
     console.log('');
 
     if (test_json.num_fails > 0 || program.printAll) {
+      var extract_error_lines = function (err) {
+        // the split is to avoid a weird thing where in PhantomJS where we get a stack trace too
+        var err_lines = err.split('\n');
+        if (err_lines.length == 1) {
+          return err_lines[0];
+        } else {
+          var ind;
+          for (ind = 0; ind < err_lines.length; ind++) {
+            var at_ind = err_lines[ind].trim().indexOf('at ');
+            if (at_ind === 0) {
+              break;
+            }
+          }
+
+          return err_lines.slice(0, ind).join('\n');
+        }
+      };
+
       var traverse_tree = function(indentation, node) {
         if (node.type == 'suite') {
           if (!node.has_subfailures && !program.printAll) return;
@@ -281,7 +299,7 @@ if (!program.outputHtml && !program.generateHtml) {
             cursor.magenta();
             console.log('- failed: '+node.text+test_json.replay);
             cursor.red();
-            console.log('          '+node.error.split("\n")[0]);  // the split is to avoid a weird thing where in PhantomJS where we get a stack trace too
+            console.log('          '+extract_error_lines(node.error));
             cursor.reset();
             console.log('');
           }