style: Use alias for StylePathCommand.

So we could drop transmute in svg_path related functions.

Differential Revision: https://phabricator.services.mozilla.com/D10140

components/style/gecko/conversions.rs

@@ -701,18 +701,11 @@ pub mod basic_shape {
 
         /// Generate a SVGPathData from StyleShapeSource if possible.
         fn to_svg_path(&self) -> Option<SVGPathData> {
-            use gecko_bindings::structs::StylePathCommand;
             use values::specified::svg_path::PathCommand;
             match self.mType {
                 StyleShapeSourceType::Path => {
                     let gecko_path = unsafe { &*self.__bindgen_anon_1.mSVGPath.as_ref().mPtr };
-                    let result: Vec<PathCommand> = gecko_path
-                        .mPath
-                        .iter()
-                        .map(|gecko: &StylePathCommand| {
-                            // unsafe: cbindgen ensures the representation is the same.
-                            unsafe { ::std::mem::transmute(*gecko) }
-                        }).collect();
+                    let result: Vec<PathCommand> = gecko_path.mPath.iter().cloned().collect();
                     Some(SVGPathData::new(result.into_boxed_slice()))
                 },
                 _ => None,

components/style/properties/gecko.mako.rs

@@ -4947,11 +4947,7 @@ fn set_style_svg_path(
         &mut shape_source.__bindgen_anon_1.mSVGPath.as_mut().mPtr.as_mut().unwrap()
     };
 
-    let iter = servo_path.commands().iter().map(|command| {
-        // unsafe: cbindgen ensures the representation is the same.
-        unsafe { transmute(*command) }
-    });
-    gecko_path.mPath.assign_from_iter_pod(iter);
+    gecko_path.mPath.assign_from_iter_pod(servo_path.commands().iter().cloned());
 
     // Setup fill-rule.
     gecko_path.mFillRule = fill;