Let nodes deallocate naturally, manually trampoline UIKit ivars

Be more aggressive with main thread punting

Trampoline setting the dataSource/delegate onto the main thread

Short-circuit the supplementary nodes method if no data source

Don't rely on assertions

Mark variable unused to fix release builds

Handle ASCollectionNode/ASTableNode deallocation better

Add some comments about new macro

AsyncDisplayKit/ASViewController.mm

@@ -19,6 +19,7 @@
 #import "ASTraitCollection.h"
 #import "ASEnvironmentInternal.h"
 #import "ASRangeControllerUpdateRangeProtocol+Beta.h"
+#import "ASInternalHelpers.h"
 
 #define AS_LOG_VISIBILITY_CHANGES 0
 
@@ -61,6 +62,11 @@
   return self;
 }
 
+- (void)dealloc
+{
+  ASPerformBackgroundDeallocation(_node);
+}
+
 - (void)loadView
 {
   ASDisplayNodeAssertTrue(!_node.layerBacked);