fix(@angular/cli): fix ever increasing lazy chunk name counter

Currently, rebuilds with lazy modules keep increasing the lazy chunk name indefinitely (.0, .1, .2, etc) for the same lazy chunk. This PR fixes that.

packages/@angular/cli/plugins/named-lazy-chunks-webpack-plugin.ts

@@ -8,14 +8,14 @@ const ImportDependency = require('webpack/lib/dependencies/ImportDependency');
 export class NamedLazyChunksWebpackPlugin extends webpack.NamedChunksPlugin {
   constructor() {
     // Append a dot and number if the name already exists.
-    const nameMap = new Map<string, boolean>();
-    function getUniqueName(baseName: string) {
+    const nameMap = new Map<string, string>();
+    function getUniqueName(baseName: string, request: string) {
       let name = baseName;
       let num = 0;
-      while (nameMap.has(name)) {
+      while (nameMap.has(name) && nameMap.get(name) !== request) {
         name = `${baseName}.${num++}`;
       }
-      nameMap.set(name, true);
+      nameMap.set(name, request);
       return name;
     }
 
@@ -34,13 +34,13 @@ export class NamedLazyChunksWebpackPlugin extends webpack.NamedChunksPlugin {
           || chunk.blocks[0].dependencies[0] instanceof ImportDependency)
       ) {
         // Create chunkname from file request, stripping ngfactory and extension.
-        const req = chunk.blocks[0].dependencies[0].request;
-        const chunkName = basename(req).replace(/(\.ngfactory)?\.(js|ts)$/, '');
+        const request = chunk.blocks[0].dependencies[0].request;
+        const chunkName = basename(request).replace(/(\.ngfactory)?\.(js|ts)$/, '');
         if (!chunkName || chunkName === '') {
           // Bail out if something went wrong with the name.
           return null;
         }
-        return getUniqueName(chunkName);
+        return getUniqueName(chunkName, request);
       }
 
       return null;