Bug 1353202 - Add nsInterfaceHashtable to opaque types r=birtles

This is needed since nsLanguageAtomService uses nsInterfaceHashtable and when
the bindings are updated we will fail the generated test
bindgen_test_layout_nsLanguageAtomService without this.

MozReview-Commit-ID: 7aYGvPrf7us

--HG--
extra : rebase_source : 4a05694dcd3ffb4f840f634bd89fee48d52d6db6

layout/style/ServoBindings.toml

@@ -274,6 +274,7 @@ opaque-types = [
     "nsTHashtable",  # <- Inheriting from inner typedefs that clang
                      #    doesn't expose properly.
     "nsRefPtrHashtable", "nsDataHashtable", "nsClassHashtable",  # <- Ditto
+    "nsInterfaceHashtable",  # <- Ditto
     "nsIDocument_SelectorCache",  # <- Inherits from nsExpirationTracker<.., 4>
     "nsIPresShell_ScrollAxis",  # <- For some reason the alignment of this is 4
                                 # for clang.