Support background colour and selection style on ASCellNodes.

Most UITableViewCell properties aren't useful in conjunction with
ASCellNode -- the system's UIView properties are unsupported for
performance reasons, and properties that configure them (e.g., content
indentation) don't affect custom node hierarchies.  This patch adds
support to _ASTableViewCell for the properties that *are* useful.

r=scottg

AsyncDisplayKit/ASCellNode.h

@@ -13,7 +13,11 @@
  */
 @interface ASCellNode : ASDisplayNode
 
-// TODO expose some UITableViewCell properties for configuration, eg, separator style
+/*
+ * ASTableView uses these properties when configuring UITableViewCells that host ASCellNodes.
+ */
+//@property (atomic, retain) UIColor *backgroundColor;
+@property (nonatomic) UITableViewCellSelectionStyle selectionStyle;
 
 @end
 

AsyncDisplayKit/ASCellNode.m

@@ -31,6 +31,9 @@
   if (!(self = [super init]))
     return nil;
 
+  // use UITableViewCell defaults
+  _selectionStyle = UITableViewCellSelectionStyleDefault;
+
   return self;
 }
 

AsyncDisplayKit/ASTableView.m

@@ -261,7 +261,7 @@ static BOOL _isInterceptedSelector(SEL sel)
     cell = [[_ASTableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:reuseIdentifier];
   }
 
-  [_rangeController configureContentView:cell.contentView forIndexPath:indexPath];
+  [_rangeController configureTableViewCell:cell forIndexPath:indexPath];
 
   return cell;
 }

AsyncDisplayKit/Details/ASRangeController.h

@@ -50,6 +50,15 @@ typedef struct {
 - (NSInteger)numberOfSizedSections;
 - (NSInteger)numberOfSizedRowsInSection:(NSInteger)section;
 
+/**
+ * Configure the specified UITableViewCell's content view, and apply properties from ASCellNode.
+ *
+ * @param cell UITableViewCell to configure.
+ *
+ * @param indexPath Index path for the node of interest.
+ */
+- (void)configureTableViewCell:(UITableViewCell *)cell forIndexPath:(NSIndexPath *)indexPath;
+
 /**
  * Add the sized node for `indexPath` as a subview of `contentView`.
  *

AsyncDisplayKit/Details/ASRangeController.mm

@@ -351,6 +351,15 @@ static BOOL ASRangeIsValid(NSRange range)
   }
 }
 
+- (void)configureTableViewCell:(UITableViewCell *)cell forIndexPath:(NSIndexPath *)indexPath
+{
+  [self configureContentView:cell.contentView forIndexPath:indexPath];
+
+  ASCellNode *node = [self sizedNodeForIndexPath:indexPath];
+  cell.backgroundColor = node.backgroundColor;
+  cell.selectionStyle = node.selectionStyle;
+}
+
 - (void)configureContentView:(UIView *)contentView forIndexPath:(NSIndexPath *)indexPath
 {
   ASCellNode *newNode = [self sizedNodeForIndexPath:indexPath];