Change Platform members to getters instead of methods.

lib/compiler/implementation/lib/io.dart

Index: lib/compiler/implementation/lib/io.dart
diff --git a/lib/compiler/implementation/lib/io.dart b/lib/compiler/implementation/lib/io.dart
index e97ccf17338d1644217b8fddbdb72579176d8c95..040925dfa298101ae82c33d38cb8a68cbdc5e618 100644
--- a/lib/compiler/implementation/lib/io.dart
+++ b/lib/compiler/implementation/lib/io.dart
@@ -61,24 +61,24 @@ class _File {
 }
 
 class _Platform {
-  static int numberOfProcessors() {
-    throw new UnsupportedOperationException('_Platform.numberOfProcessors()');
+  static int get numberOfProcessors() {
+    throw new UnsupportedOperationException('_Platform.numberOfProcessors');
   }
 
-  static String pathSeparator() {
-    throw new UnsupportedOperationException('_Platform.pathSeparator()');
+  static String get pathSeparator() {
+    throw new UnsupportedOperationException('_Platform.pathSeparator');
   }
 
-  static String operatingSystem() {
-    throw new UnsupportedOperationException('_Platform.operatingSystem()');
+  static String get operatingSystem() {
+    throw new UnsupportedOperationException('_Platform.operatingSystem');
   }
 
-  static String localHostname() {
-    throw new UnsupportedOperationException('_Platform.localHostname()');
+  static String get localHostname() {
+    throw new UnsupportedOperationException('_Platform.localHostname');
   }
 
-  static Map<String, String> environment() {
-    throw new UnsupportedOperationException('_Platform.environment()');
+  static Map<String, String> get environment() {
+    throw new UnsupportedOperationException('_Platform.environment');
   }
 }