Replace built in precompiled module with dependency (#47)

This removes the built in feature that makes the precompilation work and
add the `RustlerPrecompiled` package as dependency.

Author: philss

lib/html5ever/native.ex

@@ -9,35 +9,18 @@ defmodule Html5ever.Native do
   rustler_opts = [otp_app: :html5ever, crate: "html5ever_nif", mode: :release]
   env_config = Application.get_env(rustler_opts[:otp_app], Html5ever, [])
 
-  opts =
-    if System.get_env("HTML5EVER_BUILD") in ["1", "true"] or env_config[:build_from_source] do
-      rustler_opts
-    else
-      case Html5ever.Precompiled.download_or_reuse_nif_file(
-             rustler_opts,
-             nif_module: __MODULE__,
-             base_url: "#{github_url}/releases/download/v#{version}",
-             version: version
-           ) do
-        {:ok, new_opts} ->
-          new_opts
-
-        {:error, error} ->
-          error =
-            "Error while downloading precompiled NIF: #{error}\n\nSet HTML5EVER_BUILD=1 env var to compile the NIF from scratch. You can also configure this application to force compilation:\n\n    config :html5ever, Html5ever, build_from_source: true\n"
-
-          if Mix.env() == :prod do
-            raise error
-          else
-            Logger.debug(error)
-            rustler_opts
-          end
-      end
-    end
-
   # This module will be replaced by the NIF module after
   # loaded. It throws an error in case the NIF can't be loaded.
-  use Rustler, opts
+  if System.get_env("HTML5EVER_BUILD") in ["1", "true"] or env_config[:build_from_source] do
+    use Rustler, rustler_opts
+  else
+    use RustlerPrecompiled,
+        rustler_opts ++
+          [
+            base_url: "#{github_url}/releases/download/v#{version}",
+            version: version
+          ]
+  end
 
   def parse_sync(_binary), do: err()
   def parse_dirty(_binary), do: err()