[css-fonts] Make CSSFontFaceRule.style consistent with other CSS*Rule.style

Author: cdoublev

css-fonts-3/Overview.html

@@ -5085,7 +5085,7 @@ <h3 id=om-fontface><span class=secno>8.1. </span>The <a
 
   <pre class=idl>
 interface CSSFontFaceRule : CSSRule {
-    readonly attribute CSSStyleDeclaration style;
+    [SameObject, PutForwards=cssText] readonly attribute CSSStyleDeclaration style;
 };</pre>
 
   <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font

css-fonts-4/Overview.bs

@@ -8282,7 +8282,7 @@ interface CSSFontFaceDescriptors : CSSStyleDeclaration {
 
 [Exposed=Window]
 interface CSSFontFaceRule : CSSRule {
-	readonly attribute CSSFontFaceDescriptors style;
+	[SameObject, PutForwards=cssText] readonly attribute CSSFontFaceDescriptors style;
 };
 </pre>