Make the RootKind trait public to fix a build warning.

servo · bors-servo · Mar 7, 2016 · Mar 7, 2016 · Mar 7, 2016 · Mar 7, 2016
commit 94e6f4b9a092368c67fb2d67508035b17adaa86d
diff --git a/src/rust.rs b/src/rust.rs
@@ -171,7 +171,7 @@ impl Drop for Runtime {
 // ___________________________________________________________________________
 // Rooting API for standard JS things
 
-trait RootKind {
+pub trait RootKind {
     fn rootKind() -> ThingRootKind;
 }