build: tsconfig for editor warnings (#3791)

* build: tsconfig for editor warnings

Currently when using a code editor that uses the TypeScript language service (Webstorm / VS Code / Atom / Sublime) there will be TypeScript errors in the `.spec` files.

This is because the editor finds the `tsconfig.json` file that doesn't match the spec files. Therefore it complains about the `experimentalDecorators`.

In `angular/angular` there is a global `tsconfig` file that matches everything and is therefore fixing the editor warnings. This file is also used to compile all `.spec` files for the whole project.

We can add such a `tsconfig.json` file as well, and in the future we can use it for compiling the specs as well.

* Add docs for tsconfig files

tools/gulp/tasks/development.ts

@@ -16,7 +16,7 @@ task(':watch:devapp', () => {
 });
 
 /** Path to the demo-app tsconfig file. */
-const tsconfigPath = join(appDir, 'tsconfig.json');
+const tsconfigPath = join(appDir, 'tsconfig-build.json');
 
 task(':build:devapp:ts', tsBuildTask(tsconfigPath));
 task(':build:devapp:scss', sassBuildTask(outDir, appDir));

tools/gulp/tasks/e2e.ts

@@ -13,7 +13,7 @@ const appDir = path.join(SOURCE_ROOT, 'e2e-app');
 const outDir = DIST_E2EAPP;
 
 const PROTRACTOR_CONFIG_PATH = path.join(PROJECT_ROOT, 'test/protractor.conf.js');
-const tsconfigPath = path.join(appDir, 'tsconfig.json');
+const tsconfigPath = path.join(appDir, 'tsconfig-build.json');
 
 task(':watch:e2eapp', () => {
   watch(path.join(appDir, '**/*.ts'), [':build:e2eapp:ts']);

tools/gulp/tasks/library.ts

@@ -13,7 +13,7 @@ const inlineResources = require('../../../scripts/release/inline-resources');
 const uglify = require('uglify-js');
 
 const libraryRoot = join(SOURCE_ROOT, 'lib');
-const tsconfigPath = join(libraryRoot, 'tsconfig.json');
+const tsconfigPath = join(libraryRoot, 'tsconfig-build.json');
 
 // Paths to the different output directories.
 const materialDir = DIST_MATERIAL;

tools/gulp/tsconfig.json

@@ -1,3 +1,5 @@
+// TypeScript config file that will be used to compile the gulp tasks. The normal gulpfile will
+// use TS-Node to compile the gulp tasks at runtime.
 {
   "compilerOptions": {
     "experimentalDecorators": true,