feat(watching): allow suspend compilation

lib/MultiWatching.js

@@ -18,6 +18,18 @@ class MultiWatching {
 		}
 	}
 
+	suspend() {
+		for (const watching of this.watchings) {
+			watching.suspend();
+		}
+	}
+
+	resume() {
+		for (const watching of this.watchings) {
+			watching.resume();
+		}
+	}
+
 	close(callback) {
 		asyncLib.forEach(
 			this.watchings,

lib/Watching.js

@@ -13,6 +13,7 @@ class Watching {
 		this.handler = handler;
 		this.callbacks = [];
 		this.closed = false;
+		this.suspended = false;
 		if (typeof watchOptions === "number") {
 			this.watchOptions = {
 				aggregateTimeout: watchOptions
@@ -133,7 +134,9 @@ class Watching {
 				this.compiler.fileTimestamps = fileTimestamps;
 				this.compiler.contextTimestamps = contextTimestamps;
 				this.compiler.removedFiles = removedFiles;
-				this._invalidate();
+				if (!this.suspended) {
+					this._invalidate();
+				}
 			},
 			(fileName, changeTime) => {
 				this.compiler.hooks.invalid.call(fileName, changeTime);
@@ -166,6 +169,17 @@ class Watching {
 		}
 	}
 
+	suspend() {
+		this.suspended = true;
+	}
+
+	resume() {
+		if (this.suspended) {
+			this.suspended = false;
+			this._invalidate();
+		}
+	}
+
 	close(callback) {
 		const finalCallback = () => {
 			this.compiler.hooks.watchClose.call();