Fix: browser traverse (#309)

* Revert "fix: make getChildEntry recursively traverse the path (#301)"

This reverts commit ed6c88b.

* fix: possible browser traversal fix

packages/preview2-shim/lib/browser/filesystem.js

@@ -37,18 +37,16 @@ function getChildEntry (parentEntry, subpath, openFlags) {
   let segmentIdx;
   do {
     if (!entry || !entry.dir) throw 'not-directory';
-    segmentIdx = subpath.indexOf('/', segmentIdx);
+    segmentIdx = subpath.indexOf('/');
     const segment = segmentIdx === -1 ? subpath : subpath.slice(0, segmentIdx);
-    if (segment === '.' || segment === '')
-      /* continue traversing */;
-    else if (segment === '..')
-      throw 'no-entry';
+    if (segment === '..') throw 'no-entry';
+    if (segment === '.' || segment === '');
     else if (!entry.dir[segment] && openFlags.create)
       entry = entry.dir[segment] = openFlags.directory ? { dir: {} } : { source: new Uint8Array([]) };
     else
       entry = entry.dir[segment];
-    subpath = subpath.substring(segmentIdx + 1);
-  } while (segmentIdx !== -1);
+    subpath = subpath.slice(segmentIdx + 1);
+  } while (segmentIdx !== -1)
   if (!entry) throw 'no-entry';
   return entry;
 }