Designated methods to control dirty propagation

Summary:
Those are supposed to replace all `dirtyText`, `dirtyPropagation`, `isPropagationDirty`, `setTextComputed`, `isTextDirty` and so on.
We will use it widely soon (and remove all old ones).

Reviewed By: mmmulani

Differential Revision: D6665634

fbshipit-source-id: 3c1db7154e90b71446756f2495627b163c779996

React/Views/RCTShadowView+Layout.h

@@ -13,9 +13,28 @@
 
 @interface RCTShadowView (Layout)
 
+#pragma mark - Computed Layout-Inferred Metrics
+
 @property (nonatomic, readonly) UIEdgeInsets paddingAsInsets;
 @property (nonatomic, readonly) UIEdgeInsets borderAsInsets;
 @property (nonatomic, readonly) UIEdgeInsets compoundInsets;
 @property (nonatomic, readonly) CGSize availableSize;
 
+#pragma mark - Dirty Propagation Control
+
+/**
+ * Designated method to control dirty propagation mechanism.
+ * Dirties the shadow view (and all affected shadow views, usually a superview)
+ * in terms of layout.
+ * The default implementaion does nothing.
+ */
+- (void)dirtyLayout;
+
+/**
+ * Designated method to control dirty propagation mechanism.
+ * Clears (makes not dirty) the shadow view.
+ * The default implementaion does nothing.
+ */
+- (void)clearLayout;
+
 @end

React/Views/RCTShadowView+Layout.m

@@ -13,6 +13,8 @@
 
 @implementation RCTShadowView (Layout)
 
+#pragma mark - Computed Layout-Inferred Metrics
+
 - (UIEdgeInsets)paddingAsInsets
 {
   YGNodeRef yogaNode = self.yogaNode;
@@ -53,4 +55,16 @@ - (CGSize)availableSize
   return UIEdgeInsetsInsetRect((CGRect){CGPointZero, self.frame.size}, self.compoundInsets).size;
 }
 
+#pragma mark - Dirty Propagation Control
+
+- (void)dirtyLayout
+{
+  // The default implementaion does nothing.
+}
+
+- (void)clearLayout
+{
+  // The default implementaion does nothing.
+}
+
 @end