Bug 1270499 - Setting reflected unsigned long to out-of-range value should set to default; r=bz

This changes to match the spec, which also aligns the behavior of get
and set (get already maps out-of-range values to the default value).
There is currently no interoperable behavior here, but this aligns us
with IE -- tested in 11, hopefully true for Edge too.

On the way, I also fixed the fact that video's height and width were
being treated as signed.

dom/html/HTMLSelectElement.h

@@ -210,7 +210,7 @@ public:
   }
   void SetSize(uint32_t aSize, ErrorResult& aRv)
   {
-    SetUnsignedIntAttr(nsGkAtoms::size, aSize, aRv);
+    SetUnsignedIntAttr(nsGkAtoms::size, aSize, 0, aRv);
   }
 
   // Uses XPCOM GetType.