Remove ./mach cargo.

Not all cargo subcommands take `--manifest-path`.
Use plain `cargo` instead (rustup reads the `rust-toolchain` file)
or consider adding new mach sub-commands.

python/servo/devenv_commands.py

@@ -31,7 +31,13 @@ from servo.util import get_static_rust_lang_org_dist, get_urlopen_kwargs
 
 @CommandProvider
 class MachCommands(CommandBase):
-    def run_cargo(self, params, check=False):
+    @Command('check',
+             description='Run "cargo check"',
+             category='devenv')
+    @CommandArgument(
+        'params', default=None, nargs='...',
+        help="Command-line arguments to be passed through to cargo check")
+    def check(self, params):
         if not params:
             params = []
 
@@ -39,8 +45,7 @@ class MachCommands(CommandBase):
         self.ensure_clobbered()
         env = self.build_env()
 
-        if check:
+        params = ['check'] + params
-            params = ['check'] + params
 
         self.add_manifest_path(params)
 
@@ -50,29 +55,11 @@ class MachCommands(CommandBase):
 
         notify_build_done(self.config, elapsed, status == 0)
 
-        if check and status == 0:
+        if status == 0:
             print('Finished checking, binary NOT updated. Consider ./mach build before ./mach run')
 
         return status
 
-    @Command('cargo',
-             description='Run Cargo',
-             category='devenv')
-    @CommandArgument(
-        'params', default=None, nargs='...',
-        help="Command-line arguments to be passed through to Cargo")
-    def cargo(self, params):
-        return self.run_cargo(params)
-
-    @Command('check',
-             description='Run "cargo check"',
-             category='devenv')
-    @CommandArgument(
-        'params', default=None, nargs='...',
-        help="Command-line arguments to be passed through to cargo check")
-    def check(self, params):
-        return self.run_cargo(params, check=True)
-
     @Command('cargo-update',
              description='Same as update-cargo',
              category='devenv')