Upgrade to rules_nodejs 5.8.0 (#1150)

Fixes #1020

Author: jfirebaugh

bazel/deps.bzl

@@ -1,11 +1,25 @@
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+load("@bazel_tools//tools/build_defs/repo:utils.bzl", "maybe")
 
 def deps():
-    excludes = native.existing_rules().keys()
-
-    if "build_bazel_rules_nodejs" not in excludes:
-        http_archive(
-            name = "build_bazel_rules_nodejs",
-            sha256 = "4501158976b9da216295ac65d872b1be51e3eeb805273e68c516d2eb36ae1fbb",
-            urls = ["https://github.com/bazelbuild/rules_nodejs/releases/download/4.4.1/rules_nodejs-4.4.1.tar.gz"],
-        )
+    maybe(
+        http_archive,
+        name = "bazel_skylib",
+        sha256 = "c6966ec828da198c5d9adbaa94c05e3a1c7f21bd012a0b29ba8ddbccb2c93b0d",
+        urls = [
+            "https://github.com/bazelbuild/bazel-skylib/releases/download/1.1.1/bazel-skylib-1.1.1.tar.gz",
+            "https://mirror.bazel.build/github.com/bazelbuild/bazel-skylib/releases/download/1.1.1/bazel-skylib-1.1.1.tar.gz",
+        ],
+    )
+    maybe(
+        http_archive,
+        name = "rules_nodejs",
+        sha256 = "08337d4fffc78f7fe648a93be12ea2fc4e8eb9795a4e6aa48595b66b34555626",
+        urls = ["https://github.com/bazelbuild/rules_nodejs/releases/download/5.8.0/rules_nodejs-core-5.8.0.tar.gz"],
+    )
+    maybe(
+        http_archive,
+        name = "build_bazel_rules_nodejs",
+        sha256 = "dcc55f810142b6cf46a44d0180a5a7fb923c04a5061e2e8d8eb05ccccc60864b",
+        urls = ["https://github.com/bazelbuild/rules_nodejs/releases/download/5.8.0/rules_nodejs-5.8.0.tar.gz"],
+    )

bazel/emscripten_toolchain/BUILD.bazel

@@ -2,18 +2,13 @@ load(":toolchain.bzl", "emscripten_cc_toolchain_config_rule")
 
 package(default_visibility = ["//visibility:public"])
 
-# Name depends on rules_nodejs version being used.
-# https://github.com/emscripten-core/emsdk/issues/1020
-# https://github.com/bazelbuild/rules_nodejs/issues/3375
-node_files = "@nodejs_host//:node_files" if existing_rule("@nodejs_host//:node_files") else "@nodejs//:node_files"
-
 filegroup(
     name = "common_files",
     srcs = [
         "emscripten_config",
         "env.sh",
         "env.bat",
-        node_files,
+        "@nodejs//:node_files",
     ],
 )