fix(bazel): add support for defining the platform used for bundling spec_bundle targets

Previously the platform was hardcoded to node which worked by chance, but in some cases the platform should be
explicitly set to browser for web test which will run in a browser

Author: josephperrott

bazel/spec-bundling/index_rjs.bzl

@@ -31,7 +31,7 @@ def spec_bundle(name, deps, srcs = [], bootstrap = [], testonly = True, config =
         bundle = True,
         format = "iife",
         sourcemap = "linked",
-        platform = "node",
+        platform = kwargs.pop("platform", "node"),
         entry_point = ":%s_entrypoint" % name,
         output = "%s.spec.js" % name,
         **kwargs