isEmpty should avoid using length

Author: dwarfland

Source/String.swift

@@ -193,7 +193,13 @@ public struct SwiftString /*: Streamable*/ {
 	}
 
 	public var isEmpty : Bool {
-		return RemObjects.Elements.System.length(nativeStringValue) == 0
+		#if JAVA
+		return nativeStringValue.isEmpty()
+		#elseif CLR || ISLAND
+		return NativeString.IsNullOrEmpty(nativeStringValue)
+		#elseif COCOA
+		return nativeStringValue.length == 0
+		#endif
 	}
 
 	public func lowercased() -> SwiftString {

Source/String_Extensions.swift

@@ -105,16 +105,22 @@
 	}
 
 	public var isEmpty : Bool {
-		return length() == 0
+		#if JAVA
+		return self.isEmpty()
+		#elseif CLR || ISLAND
+		return String.IsNullOrEmpty(self)
+		#elseif COCOA
+		return length == 0
+		#endif
 	}
 
 	public func lowercased() -> NativeString {
 		#if JAVA
 		return self.toLowerCase()
-		#elseif TOFFEE
-		return self.lowercaseString
 		#elseif CLR || ISLAND
 		return self.ToLower()
+		#elseif COCOA
+		return self.lowercaseString
 		#endif
 	}