Don't store stack state for Suspense element with no fallback [perf]

lib/renderer.js

@@ -300,11 +300,11 @@ class PartialRenderer extends ReactDOMServerRenderer {
 		let node;
 		const {fallback} = element.props;
 		if (fallback !== undefined) {
-			node = this.createChild(TYPE_SUSPENSE, frame);
+			node = this.createChildWithStackState(TYPE_SUSPENSE, frame);
 			node.fallback = fallback;
 			this.suspenseNode = node;
 		} else {
-			node = this.createChild(null, frame);
+			node = this.createChild(null);
 		}
 
 		this.node = node;
@@ -324,7 +324,7 @@ class PartialRenderer extends ReactDOMServerRenderer {
 		const frame = this.stackPopOriginal.call(stack);
 
 		// Add node to tree
-		const node = this.createChild(TYPE_PROMISE, frame);
+		const node = this.createChildWithStackState(TYPE_PROMISE, frame);
 		node.element = element;
 		node.promise = promise;
 		node.resolved = false;
@@ -483,7 +483,9 @@ class PartialRenderer extends ReactDOMServerRenderer {
 		if (isRenderableElement(fallback)) suspenseFrame.children.push(fallback);
 	}
 
-	createChild(type, frame) {
+	createChildWithStackState(type, frame) {
+		const child = this.createChild(type);
+
 		// Get current contexts from new Context API
 		const {threadID} = this;
 		const contexts = [];
@@ -494,20 +496,26 @@ class PartialRenderer extends ReactDOMServerRenderer {
 			contexts.push(ctx);
 		}
 
+		// Record stackState
+		child.stackState = {
+			context: frame.context, // Contexts from legacy Context API
+			contexts, // Contexts from new Context API
+			domNamespace: frame.domNamespace,
+			currentSelectValue: this.currentSelectValue,
+			isRootElement: this.isRootElement && this.stack.length === this.nonDomFrames + 1
+		};
+
+		return child;
+	}
+
+	createChild(type) {
 		const parent = this.node;
 
 		const child = {
 			type,
 			parent,
 			parentSuspense: this.suspenseNode,
-			children: [],
-			stackState: {
-				context: frame.context, // Contexts from legacy Context API
-				contexts, // Contexts from new Context API
-				domNamespace: frame.domNamespace,
-				currentSelectValue: this.currentSelectValue,
-				isRootElement: this.isRootElement && this.stack.length === this.nonDomFrames + 1
-			}
+			children: []
 		};
 
 		parent.children.push(child);