Migrate from manual build script to copy builder (#2226)

- Remove the `tool/build.dart` file with hardcoded builders.
- Update to the latest `build_web_compilers`.
- Add a copy builder to move the `.js` files from `web/` to `lib/` and
  into the source tree.
- Change to use `-O4` dart2js arg.
- Update tests to expect `.js` for `.browser_test.dart` files.

Author: natebosch

.travis.yml

@@ -21,9 +21,9 @@ jobs:
       env: PKGS="build build_config build_daemon build_modules build_resolvers build_runner build_runner_core build_test build_vm_compilers build_web_compilers example scratch_space"
       script: ./tool/travis.sh dartfmt dartanalyzer_0
     - stage: analyze_and_format
-      name: "SDK: 2.1.0; PKGS: build, build_daemon, build_resolvers, build_runner, build_runner_core; TASKS: `dartanalyzer --fatal-warnings .`"
+      name: "SDK: 2.1.0; PKGS: build, build_daemon, build_resolvers, build_runner_core; TASKS: `dartanalyzer --fatal-warnings .`"
       dart: "2.1.0"
-      env: PKGS="build build_daemon build_resolvers build_runner build_runner_core"
+      env: PKGS="build build_daemon build_resolvers build_runner_core"
       script: ./tool/travis.sh dartanalyzer_1
     - stage: analyze_and_format
       name: "SDK: 2.2.0; PKGS: build_config, build_test; TASKS: `dartanalyzer --fatal-warnings .`"

build_runner/build.yaml

@@ -0,0 +1,25 @@
+targets:
+  $default:
+    builders:
+      build_web_compilers:entrypoint:
+        options:
+          compiler: dart2js
+          dart2js_args:
+            - -O4
+        generate_for:
+          - web/graph_viz_main.dart
+          - web/hot_reload_client.dart
+      build_runner:client_js_copy_builder:
+        enabled: true
+builders:
+  client_js_copy_builder:
+    import: "tool/builders.dart"
+    builder_factories:
+        - copyCompiledJs
+    build_extensions:
+      web/graph_viz_main.dart.js:
+        - lib/src/server/graph_viz_main.dart.js
+      web/hot_reload_client.dart.js:
+        - lib/src/server/build_updates_client/hot_reload_client.dart.js
+    auto_apply: none
+    build_to: source