build: Introduce Bazel build rules

So far this just compiles the core and common packages.

packages/common/BUILD

@@ -0,0 +1,13 @@
+package(default_visibility=["//visibility:public"])
+load("@io_bazel_rules_typescript//:defs.bzl", "ts_library")
+
+ts_library(
+    name = "common",
+    srcs = glob(["**/*.ts"], exclude=[
+      "test/**",
+      "testing/**",
+    ]),
+    module_name = "@angular/common",
+    deps = ["//packages/core"],
+    tsconfig = ":tsconfig-build.json",
+)

packages/common/tsconfig-build.json

@@ -1,35 +1,41 @@
 {
+  "angularCompilerOptions": {
+    "annotateForClosureCompiler": true,
+    "strictMetadataEmit": true,
+    "flatModuleOutFile": "index.js",
+    "flatModuleId": "@angular/common"
+  },
+
   "compilerOptions": {
-    "baseUrl": ".",
-    "declaration": true,
     "stripInternal": true,
-    "experimentalDecorators": true,
     "strictNullChecks": true,
     "noImplicitAny": true,
     "noFallthroughCasesInSwitch": true,
     "module": "es2015",
     "moduleResolution": "node",
+    "target": "es2015",
+    "skipLibCheck": true,
+    "lib": [ "es2015", "dom" ],
+    // don't auto-discover @types/node, it results in a ///<reference in the .d.ts output
+    "types": [],
+
+    /**
+     * The rest of the file is configuration that's overridden by bazel.
+     * It can be removed after we fully migrate.
+     */
+    "baseUrl": ".",
+    "declaration": true,
+    "experimentalDecorators": true,
     "outDir": "../../dist/packages/common",
     "paths": {
       "@angular/core": ["../../dist/packages/core"]
     },
     "rootDir": ".",
     "sourceMap": true,
-    "inlineSources": true,
-    "target": "es2015",
-    "skipLibCheck": true,
-    "lib": [ "es2015", "dom" ],
-    // don't auto-discover @types/node, it results in a ///<reference in the .d.ts output
-    "types": []
+    "inlineSources": true
   },
   "files": [
     "public_api.ts",
     "../../node_modules/zone.js/dist/zone.js.d.ts"
-  ],
-  "angularCompilerOptions": {
-    "annotateForClosureCompiler": true,
-    "strictMetadataEmit": true,
-    "flatModuleOutFile": "index.js",
-    "flatModuleId": "@angular/common"
-  }
+  ]
 }