Merge pull request #25610 from RyanCavanaugh/buildOnWatchStartup

When running with -w, do an initial compilation

src/compiler/tsbuild.ts

@@ -488,6 +488,7 @@ namespace ts {
         }
 
         if (watch) {
+            builder.buildAllProjects();
             builder.startWatching();
             return undefined;
         }