[turbofan] More broker cleanups.

- Provide getters for all member variables.
- Add missing flags for cycle detection.
- Be more consistent in stylistic matters.

Bug: v8:7790
Change-Id: I87c3901b203acc4254ec48f5cc895b2e68ff32aa
Reviewed-on: https://chromium-review.googlesource.com/1196431
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55755}

src/compiler/js-heap-broker.h

@@ -469,6 +469,8 @@ class V8_EXPORT_PRIVATE JSHeapBroker : public NON_EXPORTED_BASE(ZoneObject) {
   ObjectData* GetData(Handle<Object>) const;
   // Never returns nullptr.
   ObjectData* GetOrCreateData(Handle<Object>);
+  // Like the previous but wraps argument in handle first (for convenience).
+  ObjectData* GetOrCreateData(Object*);
 
   void Trace(const char* format, ...) const;