AppKit: CPLayoutManager, CPStringDrawing, CPMenu, CPCookie PLATFORM conditional removal

- 8 PLATFORM blocks resolved across four files: runtime CPDOMAvailable
  guards (3 wrapped, 2 early returns, 3 if/else preserving existing
  CommonJS branches)
- CPMenu: @global _CPDOMEventStop declared; its definition resides in
  the DOM-only CPPlatformWindow+DOM category
- zero preprocessor directives remain in these files
- work-in-progress towards complete removal of CPP directives

AppKit/CPTextView/CPLayoutManager.j

@@ -28,6 +28,7 @@
 @import "CGContext.j"
 @import "CPTypesetter.j"
 @import "CPFont.j"
+@import "CPCompatibility.j"
 
 @global _MakeRangeFromAbs
 @global document
@@ -297,9 +298,10 @@ _oncontextmenuhandler = function () { return false; };
 
     [_typesetter layoutGlyphsInLayoutManager:self startingAtGlyphIndex:startIndex maxNumberOfLineFragments:-1 nextGlyphIndex:nil];
 
-#if PLATFORM(DOM)
-    [self _cleanUpDOM];
-#endif
+    if (CPDOMAvailable)
+    {
+        [self _cleanUpDOM];
+    }
 
     _isValidatingLayoutAndGlyphs = NO;
 }
@@ -1145,7 +1147,8 @@ var _objectsInRange = function(aList, aRange)
     if (!aString || aString.length === 0)
         return nil;
 
-#if PLATFORM(DOM)
+    if (!CPDOMAvailable) return nil;
+
     var style,
         span = document.createElement("span");
 
@@ -1196,9 +1199,6 @@ var _objectsInRange = function(aList, aRange)
         span.textContent = aString;
 
     return span;
-#else
-    return nil;
-#endif
 }
 
 - (id)initWithRange:(CPRange)aRange textContainer:(CPTextContainer)aContainer textStorage:(CPTextStorage)textStorage