fixup! Enable WPT in Linux taskcluster CI.

etc/taskcluster/decision_task.py

@@ -112,13 +112,16 @@ def mocked_only():
 }
 unix_build_env = {
 }
+# Setting up a virtualenv for mach can require compiling native python modules.
+linux_env = {
+    "CC": "clang",
+    "CXX": "clang++",
+}
 linux_build_env = {
     "SHELL": "/bin/dash",  # For SpiderMonkey’s build system
     "CCACHE": "sccache",
     "RUSTC_WRAPPER": "sccache",
     "SCCACHE_IDLE_TIMEOUT": "1200",
-    "CC": "clang",
-    "CXX": "clang++",
 }
 macos_build_env = {}
 windows_build_env = {
@@ -151,7 +154,7 @@ def linux_tidy_unit_untrusted():
         .with_treeherder("Linux x64", "Tidy+Unit")
         .with_max_run_time_minutes(60)
         .with_dockerfile(dockerfile_path("build"))
-        .with_env(**build_env, **unix_build_env, **linux_build_env)
+        .with_env(**build_env, **unix_build_env, **linux_env, **linux_build_env)
         .with_repo()
         .with_script("""
             ./mach test-tidy --no-progress --all
@@ -521,7 +524,11 @@ def linux_wpt():
         .find_or_create("build.linux_x64_release~assertions" + CONFIG.task_id())
     )
     def linux_run_task(name):
-        return linux_task(name).with_dockerfile(dockerfile_path("run"))
+        return (
+            linux_task(name)
+            .with_env(**linux_env)
+            .with_dockerfile(dockerfile_path("run"))
+        )
     wpt_chunks("Linux x64", linux_run_task, release_build_task, repo_dir="/repo",
                total_chunks=2, processes=24)
 
@@ -758,7 +765,7 @@ def linux_build_task(name, *, build_env=build_env):
         .with_index_and_artifacts_expire_in(build_artifacts_expire_in)
         .with_max_run_time_minutes(60)
         .with_dockerfile(dockerfile_path("build"))
-        .with_env(**build_env, **unix_build_env, **linux_build_env)
+        .with_env(**build_env, **unix_build_env, **linux_env, **linux_build_env)
         .with_repo()
     )
 

etc/taskcluster/docker/base.dockerfile

@@ -19,6 +19,9 @@ RUN \
         python-pip \
         python-dev \
         #
+        # Building native python dependencies
+        clang \
+        #
         # Installing rustup and sccache (build dockerfile) or fetching build artifacts (run tasks)
         curl && \
     # Running mach

etc/taskcluster/docker/build.dockerfile

@@ -18,7 +18,6 @@ RUN \
         autoconf2.13 \
         #
         # Bindgen (for SpiderMonkey bindings)
-        clang \
         llvm \
         llvm-dev \
         #