[Layout] Layout API based on content area (#2110)

* Initial commit for adding a size constraint to ASLayoutable's

* Some more commits

* Fix sample projects in extra/

* Remove preferredFrameSize test of ASEditableTextNode

* Remove preferredFrameSize from examples_extra

* Add deprecation warning to -[ASDisplayNode preferredFrameSize]

* Add deprecation warning to -[ASDisplayNode measureWithSizeRange:]

* Commit

* Commit

* Remove ASRelativeSizeRange

* Make ASRelativeSize private

* Adjust examples

* Improve setting of -[ASLayoutable size] with points or fractions

* Add ASWrapperLayoutSpec

* Improve creation of ASRelativeDimension

* Add `preferredFrameSize` back and add deprecated logging

* Add `layoutSpecBlock` setter and getter and add locking for it

* Add better documentation and fix macros to create ASRelativeDimension

* Create new ASSizeRangeMake with just a CGSize as parameter

* Update Kitten and Social App Layout example

* Add layoutThatFits: and deprecate measure:

* Rename ASRelativeDimension to ASDimension

* Fix examples for ASDimension renaming

* Remove fancy height and width setter

* Fix ASDimension helper

* Rename -[ASLayout layoutableObject] to -[ASLayout layoutable]

* Update layout related methods and more clearer documentation around how to use it

* Deprecate old ASLayout class constructors

* Don't unnecessary recalculate layout if constrained or parent size did not change

* Use shared pointer for ASDisplayNodeLayout

* Fix rebase conflicts

* Add documentation and move implementation in mm file of ASDisplayNodeLayout

* Fix test errors

* Rename ASSize to ASLayoutableSize

* Address comments

* Rename setSizeFromCGSize to setSizeWithCGSize

* Improve inline functions in ASDimension

* Fix rebase conflicts

examples_extra/SynchronousConcurrency/Sample/AsyncTableViewController.m

@@ -30,24 +30,12 @@
 
 @implementation AsyncTableViewController
 
-#pragma mark -
-#pragma mark UIViewController.
+#pragma mark - UIViewController.
 
 - (instancetype)init
 {
   if (!(self = [super init]))
     return nil;
-
-  _tableView = [[ASTableView alloc] initWithFrame:CGRectZero style:UITableViewStylePlain];
-  _tableView.separatorStyle = UITableViewCellSeparatorStyleNone;
-  _tableView.asyncDataSource = self;
-  _tableView.asyncDelegate = self;
-  
-  ASRangeTuningParameters tuningParameters;
-  tuningParameters.leadingBufferScreenfuls = 0.5;
-  tuningParameters.trailingBufferScreenfuls = 1.0;
-  [_tableView setTuningParameters:tuningParameters forRangeType:ASLayoutRangeTypePreload];
-  [_tableView setTuningParameters:tuningParameters forRangeType:ASLayoutRangeTypeRender];
   
   self.tabBarItem = [[UITabBarItem alloc] initWithTabBarSystemItem:UITabBarSystemItemFeatured tag:0];
   self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemRedo
@@ -66,22 +54,30 @@
 {
   [super viewDidLoad];
 
+  _tableView = [[ASTableView alloc] initWithFrame:self.view.bounds style:UITableViewStylePlain];
+  _tableView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
+  _tableView.separatorStyle = UITableViewCellSeparatorStyleNone;
+  _tableView.asyncDataSource = self;
+  _tableView.asyncDelegate = self;
+  
+  ASRangeTuningParameters tuningParameters;
+  tuningParameters.leadingBufferScreenfuls = 0.5;
+  tuningParameters.trailingBufferScreenfuls = 1.0;
+  [_tableView setTuningParameters:tuningParameters forRangeType:ASLayoutRangeTypePreload];
+  [_tableView setTuningParameters:tuningParameters forRangeType:ASLayoutRangeTypeRender];
+  
   [self.view addSubview:_tableView];
 }
 
-- (void)viewWillLayoutSubviews
-{
-  _tableView.frame = self.view.bounds;
-}
+#pragma mark - ASTableView.
 
-#pragma mark -
-#pragma mark ASTableView.
-
-- (ASCellNode *)tableView:(ASTableView *)tableView nodeForRowAtIndexPath:(NSIndexPath *)indexPath
+- (ASCellNodeBlock)tableView:(ASTableView *)tableView nodeBlockForRowAtIndexPath:(NSIndexPath *)indexPath
 {
-  RandomCoreGraphicsNode *elementNode = [[RandomCoreGraphicsNode alloc] init];
-  elementNode.preferredFrameSize = CGSizeMake(320, 100);
-  return elementNode;
+  return ^{
+    RandomCoreGraphicsNode *elementNode = [[RandomCoreGraphicsNode alloc] init];
+    elementNode.size = ASRelativeSizeRangeMakeWithExactCGSize(CGSizeMake(320, 100));
+    return elementNode;
+  };
 }
 
 - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section

examples_extra/SynchronousConcurrency/Sample/RandomCoreGraphicsNode.m

@@ -92,6 +92,8 @@
 
 - (void)layout
 {
+  [super layout];
+  
   CGSize boundsSize = self.bounds.size;
   CGSize textSize = _textNode.calculatedSize;
   CGRect textRect = CGRectMake(roundf((boundsSize.width - textSize.width) / 2.0),