Bug 1441205 - XPTMethodDescriptor::result is unused. r=njn

This sounds weird, but either:
1) A method is notxpcom, so it can't be called from script and the XPT
information is unused.
2) A method is not notxpcom, in which case the result type is nsresult.

MozReview-Commit-ID: a7SRJn8PlP

--HG--
extra : rebase_source : 457051a47dd3f1f2f49b5f11ef3e5138f9d814e1

xpcom/reflect/xptinfo/xptinfo.h

@@ -198,8 +198,6 @@ public:
             NS_PRECONDITION(idx < GetParamCount(),"bad arg");
             return params[idx];
         }
-    const nsXPTParamInfo GetResult() const
-        {return result;}
 private:
     nsXPTMethodInfo();  // no implementation
 // NO DATA - this a flyweight wrapper

xpcom/typelib/xpt/xpt_struct.cpp

@@ -316,7 +316,12 @@ DoMethodDescriptor(XPTArena *arena, NotNull<XPTCursor*> cursor,
             return false;
     }
 
-    if (!DoParamDescriptor(arena, cursor, &md->result, id))
+    // |result| appears in the on-disk format but it isn't used,
+    // because a method is either notxpcom, in which case it can't be
+    // called from script so the XPT information is irrelevant, or the
+    // result type is nsresult.
+    XPTParamDescriptor result;
+    if (!DoParamDescriptor(arena, cursor, &result, id))
         return false;
 
     return true;

xpcom/typelib/xpt/xpt_struct.h

@@ -286,7 +286,7 @@ struct XPTParamDescriptor {
 struct XPTMethodDescriptor {
     char                *name;
     XPTParamDescriptor  *params;
-    XPTParamDescriptor  result;
+    //XPTParamDescriptor  result; // Present on disk, omitted here.
     uint8_t             flags;
     uint8_t             num_args;
 };