Walk up data frames for nested @partial-block

The root cause of #1218 is that `invokePartial` creates a stack of data frames
for nested partial blocks, but `resolvePartial` always uses the value at top of
the stack without "popping" it. The result is an infinite recursive loop, as
references to `@partial-block` in the partial at the top of the stack resolve to
itself.

So, walk up the stack of data frames when evaluating. This is accomplished by
1) setting the `partial-block` property to `noop` after use and
2) using `_parent['partial-block']` if `partial-block` is `noop`

Fix #1218

lib/handlebars/runtime.js

@@ -210,7 +210,12 @@ export function wrapProgram(container, i, fn, data, declaredBlockParams, blockPa
 export function resolvePartial(partial, context, options) {
   if (!partial) {
     if (options.name === '@partial-block') {
-      partial = options.data['partial-block'];
+      let data = options.data;
+      while (data['partial-block'] === noop) {
+        data = data._parent;
+      }
+      partial = data['partial-block'];
+      data['partial-block'] = noop;
     } else {
       partial = options.partials[options.name];
     }