build: consolidate tsc to ease migration to @types/ based typings delivery

I actually tried to use @types/* directly but came across several issues which prevented me
from switching over:
- https://github.com/Microsoft/TypeScript/issues/8715
- https://github.com/Microsoft/TypeScript/issues/8723

gulpfile.js

@@ -325,7 +325,7 @@ gulp.task('enforce-format', function() {
   });
 });
 
-gulp.task('lint', ['build.tools'], function() {
+gulp.task('lint', function() {
   var tslint = require('gulp-tslint');
   // Built-in rules are at
   // https://github.com/palantir/tslint#supported-rules