Bug 1457813 - Part 2: Replace non-asserting NS_PRECONDITIONs with MOZ_ASSERTs. r=froydnj

s/NS_PRECONDITION/MOZ_ASSERT/ and reindent

MozReview-Commit-ID: KuUsnVe2h8L

parser/html/nsHtml5StreamParser.cpp

@@ -886,7 +886,7 @@ nsHtml5StreamParser::OnStartRequest(nsIRequest* aRequest, nsISupports* aContext)
 {
   MOZ_RELEASE_ASSERT(STREAM_NOT_STARTED == mStreamState,
                      "Got OnStartRequest when the stream had already started.");
-  NS_PRECONDITION(
+  MOZ_ASSERT(
     !mExecutor->HasStarted(),
     "Got OnStartRequest at the wrong stage in the executor life cycle.");
   NS_ASSERTION(NS_IsMainThread(), "Wrong thread!");