Remove the Document.charset setter (making it readonly)

LayoutTests/fast/dom/Document/document-charset-expected.txt

Index: LayoutTests/fast/dom/Document/document-charset-expected.txt
diff --git a/LayoutTests/fast/dom/Document/document-charset-expected.txt b/LayoutTests/fast/dom/Document/document-charset-expected.txt
index c4569e83f281f4d889f3a49f4b1637da42b370d5..b76f4731152e44ac1119f4b488025ce3b03b162f 100644
--- a/LayoutTests/fast/dom/Document/document-charset-expected.txt
+++ b/LayoutTests/fast/dom/Document/document-charset-expected.txt
@@ -1,4 +1,3 @@
-CONSOLE WARNING: Setting 'Document.charset' is deprecated. Please use '<meta charset="UTF-8">' instead.
 Initial
 
  document.charset: KOI8-R
@@ -9,22 +8,12 @@ Initial
 
  document.inputEncoding: KOI8-R
 
-Setting charset to UTF-8...
+Setting charset to UTF-8... (expected to have no effect)
 
- document.charset: UTF-8
-
- document.defaultCharset: defined
-
- document.characterSet: UTF-8
-
- document.inputEncoding: UTF-8
-
-Setting characterSet to KOI8-R (expected to fail, matching Firefox)...
-
- document.charset: UTF-8
+ document.charset: KOI8-R
 
  document.defaultCharset: defined
 
- document.characterSet: UTF-8
+ document.characterSet: KOI8-R
 
- document.inputEncoding: UTF-8
+ document.inputEncoding: KOI8-R