revert the work done in earlier commit with anchor properties

revert commit 1fe19578c2 which changed `anchor()` values to `position-area`.

I'm not sure what compelled me to do that change initially, except the easier to understand syntax.  Hopefully it wasn't important.

But oddbird polyfill expects `anchor()` values, which it converts to pixel values for positioning.

client/components/Anchored.less

@@ -4,8 +4,6 @@
 	position          : absolute;
 	visibility        : hidden;
 	justify-self      : anchor-center;
-	@supports (inset-block-start: anchor(bottom)) {
 	inset-block-start : anchor(bottom);
-	}
 	&.active { visibility : visible; }
 }

client/components/anchorPositioningPolyfill.js

@@ -8,27 +8,20 @@ let polyfillPromise;
 // look for `anchorName` in the computed styles
 const supportsAnchorPositioning = ()=>'anchorName' in document.documentElement.style;
 
-// wait for initial render
-const afterInitialRender = ()=>new Promise((resolve)=>{
-	requestAnimationFrame(()=>{
-		requestAnimationFrame(resolve);
-	});
-});
-
 export const bootstrapAnchorPositioningPolyfill = ()=>{
 	if(supportsAnchorPositioning()) return Promise.resolve(false);
 	if(polyfillPromise) return polyfillPromise;
 
-	polyfillPromise = afterInitialRender()
+	polyfillPromise = (async ()=>{
-		.then(async ()=>{
+		try {
 			const { default: polyfill } = await import('@oddbird/css-anchor-positioning/fn');
 			await polyfill();
 			return true;
-		})
+		} catch (error){
-		.catch((error)=>{
 			polyfillPromise = undefined;
 			throw error;
-		});
+		}
+	})();
 
 	return polyfillPromise;
 };

client/components/dropdown/dropdown.less

@@ -6,16 +6,18 @@
 }
 
 .menu-list {
-	position         : absolute;
+	position         : fixed;
 	z-index          : 1000;
-	position-area : block-end span-inline-end;
+	top              : anchor(bottom);
+	left             : anchor(left);
 	position-try: flip-inline flip-block;
 	color: inherit;   // [popover] gets a `canvastext` color value from useragent.
 	> .menu-wrapper {
 		position:relative;
 		> .menu-list {
 			margin: 0 0px;
-			position-area: inline-end span-block-end;
+			top  : anchor(top);
+			left : anchor(right);
 			position-try: flip-inline;
 		}
 	}