Bug 1840184 - Remove redundant FileSystemWritableFileStreamChild shut…

…down check. r=dom-storage-reviewers,janv

Both use cases of the getter of the WritableFileStream pointer are already handling the case where the result is null. In the debug-only check of whether all streams are closed, null result is possible, as evidenced by the bug. When the streams are closed at shutdown, we assume that closing takes place only once and the result is not null but since the second closing can be handled as a no-op, it is not necessary enforce this expectation, following declarative API design.

Differential Revision: https://phabricator.services.mozilla.com/D202589

dom/fs/child/FileSystemWritableFileStreamChild.h

@@ -21,7 +21,6 @@ class FileSystemWritableFileStreamChild
   NS_INLINE_DECL_REFCOUNTING(FileSystemWritableFileStreamChild, override)
 
   FileSystemWritableFileStream* MutableWritableFileStreamPtr() const {
-    MOZ_ASSERT(mStream);
     return mStream;
   }