Auto merge of #8286 - eefriedman:no-move, r=nox

Remove unnecessary uses of #[no_move]

The patch makes RootCollection a bit safer by making the StackRootTLS hold
it in place.

RootedVec was doing an extremely delicate dance and just hoping nobody
messed it up; switch to a Box to be safe.

CodeGenRust seemed to be using no_move for no particularly good reason.

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components/script/dom/bindings/codegen/CodegenRust.py

@@ -4927,7 +4927,6 @@ class CGDictionary(CGThing):
                        for m in self.memberInfo]
 
         return (string.Template(
-                "#[no_move]\n" +
                 "pub struct ${selfName} {\n" +
                 "${inheritance}" +
                 "\n".join(memberDecls) + "\n" +