[fuchsia] Export CastChannel FIDL service from CastRunner.

Cast components now offer a CastChannel API via their ComponentController
interface.

Supporting changes:
* Decouple construction and navigation for WebComponents, so that
  bindings like CastChannel can be attached to a Frame in the interim.
* Add a dynamic Cast app registry to FakeApplicationConfigManager.
* Replace fine-grained Fuchsia targets in //BUILD.gn with a
  //fuchsia:gn_all metatarget.
* Remove cast_runner_unittests.

Bug: 910799
Change-Id: I18447c08dad9cbfa017d6b2ebba9b635c3dc4921
Reviewed-on: https://chromium-review.googlesource.com/c/1416890
Commit-Queue: Kevin Marshall <kmarshall@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Auto-Submit: Kevin Marshall <kmarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#628015}

diff --git a/BUILD.gn b/BUILD.gn
index 281dccc8a..8571278 100644
--- a/BUILD.gn
+++ b/BUILD.gn

@@ -218,7 +218,9 @@
   } else if (is_fuchsia) {
     deps += [
       ":d8_fuchsia",
-      "build/fuchsia/fidlgen_js:fidlgen_js_unittests",
+      "//build/fuchsia/fidlgen_js:fidlgen_js_unittests",
+      "//fuchsia:gn_all",
+      "//headless",
     ]
   }
 
@@ -763,15 +765,6 @@
     }
   }
 
-  if (is_fuchsia) {
-    deps += [
-      "//fuchsia:webrunner_unittests",
-      "//fuchsia/http:http_service_tests",
-      "//fuchsia/runners:cast_runner_unittests",
-      "//headless",
-    ]
-  }
-
   if (enable_vulkan) {
     deps += [ "//gpu/vulkan/demo" ]
   }