Change Platform members to getters instead of methods.

tests/standalone/io/file_error_test.dart

Index: tests/standalone/io/file_error_test.dart
diff --git a/tests/standalone/io/file_error_test.dart b/tests/standalone/io/file_error_test.dart
index 40f2b62c9b3b2cfb7c4a05c7efecd16e7b0683f7..6aef13af9f7691a865fb769ae31775e01c5c42b5 100644
--- a/tests/standalone/io/file_error_test.dart
+++ b/tests/standalone/io/file_error_test.dart
@@ -18,11 +18,11 @@ bool checkNonExistentFileException(e, str) {
   Expect.isTrue(e is FileIOException);
   Expect.isTrue(e.osError != null);
   Expect.isTrue(e.toString().indexOf(str) != -1);
-  if (Platform.operatingSystem() == "linux") {
+  if (Platform.operatingSystem == "linux") {
     Expect.isTrue(e.toString().indexOf("No such file or directory") != -1);
-  } else if (Platform.operatingSystem() == "macos") {
+  } else if (Platform.operatingSystem == "macos") {
     Expect.isTrue(e.toString().indexOf("No such file or directory") != -1);
-  } else if (Platform.operatingSystem() == "windows") {
+  } else if (Platform.operatingSystem == "windows") {
     Expect.isTrue(
         e.toString().indexOf(
             "The system cannot find the file specified") != -1);
@@ -116,13 +116,13 @@ bool checkCreateInNonExistentDirectoryException(e) {
   Expect.isTrue(e is FileIOException);
   Expect.isTrue(e.osError != null);
   Expect.isTrue(e.toString().indexOf("Cannot create file") != -1);
-  if (Platform.operatingSystem() == "linux") {
+  if (Platform.operatingSystem == "linux") {
     Expect.isTrue(e.toString().indexOf("No such file or directory") != -1);
     Expect.equals(2, e.osError.errorCode);
-  } else if (Platform.operatingSystem() == "macos") {
+  } else if (Platform.operatingSystem == "macos") {
     Expect.isTrue(e.toString().indexOf("No such file or directory") != -1);
     Expect.equals(2, e.osError.errorCode);
-  } else if (Platform.operatingSystem() == "windows") {
+  } else if (Platform.operatingSystem == "windows") {
     Expect.isTrue(
         e.toString().indexOf(
             "The system cannot find the path specified") != -1);
@@ -156,11 +156,11 @@ bool checkFullPathOnNonExistentDirectoryException(e) {
   Expect.isTrue(e is FileIOException);
   Expect.isTrue(e.osError != null);
   Expect.isTrue(e.toString().indexOf("Cannot retrieve full path") != -1);
-  if (Platform.operatingSystem() == "linux") {
+  if (Platform.operatingSystem == "linux") {
     Expect.isTrue(e.toString().indexOf("No such file or directory") != -1);
-  } else if (Platform.operatingSystem() == "macos") {
+  } else if (Platform.operatingSystem == "macos") {
     Expect.isTrue(e.toString().indexOf("No such file or directory") != -1);
-  } else if (Platform.operatingSystem() == "windows") {
+  } else if (Platform.operatingSystem == "windows") {
     Expect.isTrue(
         e.toString().indexOf(
             "The system cannot find the file specified") != -1);
@@ -196,11 +196,11 @@ bool checkDirectoryInNonExistentDirectoryException(e) {
   Expect.isTrue(e.osError != null);
   Expect.isTrue(
       e.toString().indexOf("Cannot retrieve directory for file") != -1);
-  if (Platform.operatingSystem() == "linux") {
+  if (Platform.operatingSystem == "linux") {
     Expect.isTrue(e.toString().indexOf("No such file or directory") != -1);
-  } else if (Platform.operatingSystem() == "macos") {
+  } else if (Platform.operatingSystem == "macos") {
     Expect.isTrue(e.toString().indexOf("No such file or directory") != -1);
-  } else if (Platform.operatingSystem() == "windows") {
+  } else if (Platform.operatingSystem == "windows") {
     Expect.isTrue(
         e.toString().indexOf(
             "The system cannot find the file specified") != -1);