Removes css_group() from public API.

This actually isn't necessary because it's only use case was `prerender_resources(inline_styles = [...])`, but that has no valid external use case because `prerender_resources()` is intended for rendering non-HTML content (binary/text/JSON/... files). Users who want to render HTML, should be using `prerender_pages()` or `prerender_pages_unbundled()`, and not calling `prerender_resources()` directly.

`prerender_resources_internal()` allows use of `inline_styles` but is only available internally in `rules_prerender`, and is *not* public API.

index.bzl

@@ -36,16 +36,11 @@ load(
     "//packages/rules_prerender:web_resources_devserver.bzl",
     _web_resources_devserver = "web_resources_devserver",
 )
-load(
-    "//packages/rules_prerender/css:css_group.bzl",
-    _css_group = "css_group",
-)
 load(
     "//packages/rules_prerender/css:css_library.bzl",
     _css_library = "css_library",
 )
 
-css_group = _css_group
 css_library = _css_library
 extract_single_resource = _extract_single_resource
 inject_resources = _inject_resources

packages/rules_prerender/prerender_pages_unbundled.bzl

@@ -5,7 +5,7 @@ load("@npm//@bazel/concatjs:index.bzl", "ts_library")
 load("//common:label.bzl", "absolute", "file_path_of")
 load(":entry_points.bzl", "script_entry_point", "style_entry_point")
 load(":prerender_component.bzl", "prerender_component")
-load(":prerender_resources.bzl", "prerender_resources")
+load(":prerender_resources.bzl", "prerender_resources_internal")
 load(":web_resources.bzl", "WebResourceInfo", "web_resources")
 
 def prerender_pages_unbundled(
@@ -126,7 +126,7 @@ def prerender_pages_unbundled(
         if src.endswith(".ts")
         else src
     )
-    prerender_resources(
+    prerender_resources_internal(
         name = annotated,
         entry_point = file_path_of(absolute(js_src)),
         inline_styles = ":%s" % component_inline_styles,

packages/rules_prerender/prerender_resources.bzl

@@ -22,7 +22,7 @@ def prerender_resources(
 
     The file listed in `entry` must be included in the `data` attribute as a
     CommonJS module with a default export of the type:
-    
+
     ```
     () => Iterable<PrerenderResource> | Promise<Iterable<PrerenderResource>>
         | AsyncIterable<PrerenderResource>
@@ -48,7 +48,7 @@ def prerender_resources(
     Outputs:
         %{name}: A `web_resources()`-compatible target containing all the files
             generated at their corresponding locations.
-    
+
     Args:
         name: The name of this rule.
         entry_point: The JavaScript entry point to use to execute the given
@@ -63,6 +63,27 @@ def prerender_resources(
         testonly: See https://docs.bazel.build/versions/master/be/common-definitions.html.
         visibility: See https://docs.bazel.build/versions/master/be/common-definitions.html.
     """
+    prerender_resources_internal(
+        name = name,
+        entry_point = entry_point,
+        data = data,
+        testonly = testonly,
+        visibility = visibility,
+        # Not supported in public API because this would require exposing `css_group()` or
+        # `css_binaries()` and is only useful for prerendering HTML pages which should be
+        # done with `prerender_pages()`, not `prerender_resources()`.
+        inline_styles = None,
+    )
+
+def prerender_resources_internal(
+    name,
+    entry_point,
+    data,
+    inline_styles = None,
+    testonly = None,
+    visibility = None,
+):
+    """Internal version of `prerender_resources()` which allows `inline_styles` usage."""
     # Validate `entry_point`.
     if "/" not in entry_point or not is_js_file(entry_point):
         fail(("`entry_point` (%s) *must* be a workspace-relative path of the"