Use captureStackTrace for error handler

Provides more stable error stack reporting when running under v8 environments.

lib/handlebars/exception.js

@@ -19,6 +19,10 @@ function Exception(message, node) {
     this[errorProps[idx]] = tmp[errorProps[idx]];
   }
 
+  if (Error.captureStackTrace) {
+    Error.captureStackTrace(this, Exception);
+  }
+
   if (loc) {
     this.lineNumber = line;
     this.column = column;