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/HTMLTextAreaElement.h

@@ -179,7 +179,7 @@ public:
     if (aCols == 0) {
       aError.Throw(NS_ERROR_DOM_INDEX_SIZE_ERR);
     } else {
-      SetUnsignedIntAttr(nsGkAtoms::cols, aCols, aError);
+      SetUnsignedIntAttr(nsGkAtoms::cols, aCols, DEFAULT_COLS, aError);
     }
   }
   bool Disabled()
@@ -247,7 +247,7 @@ public:
     if (aRows == 0) {
       aError.Throw(NS_ERROR_DOM_INDEX_SIZE_ERR);
     } else {
-      SetUnsignedIntAttr(nsGkAtoms::rows, aRows, aError);
+      SetUnsignedIntAttr(nsGkAtoms::rows, aRows, DEFAULT_ROWS_TEXTAREA, aError);
     }
   }
   // XPCOM GetWrap is fine