feat(compiler): Added "strictMetadataEmit" option to ngc (#10951)

ngc can now validate metadata before emitting to verify it doesn't
contain an error symbol that will result in a runtime error if
it is used by the StaticReflector.

To enable this add the section,

  "angularCompilerOptions": {
    "strictMetadataEmit": true
  }

to the top level of the tsconfig.json file passed to ngc.

Enabled metadata validation for packages that are intended to be
used statically.

modules/@angular/http/tsconfig-es2015.json

@@ -21,5 +21,8 @@
     "index.ts",
     "testing.ts",
     "../../../node_modules/zone.js/dist/zone.js.d.ts"
-  ]
+  ],
+  "angularCompilerOptions": {
+    "strictMetadataEmit": true
+  }
 }

modules/@angular/http/tsconfig-es5.json

@@ -22,5 +22,8 @@
     "index.ts",
     "testing.ts",
     "../../../node_modules/zone.js/dist/zone.js.d.ts"
-  ]
+  ],
+  "angularCompilerOptions": {
+    "strictMetadataEmit": true
+  }
 }