Revert change to Platform.excutable and add Platform.resolvedExecutable

tests/standalone/io/platform_test.dart

Index: tests/standalone/io/platform_test.dart
diff --git a/tests/standalone/io/platform_test.dart b/tests/standalone/io/platform_test.dart
index 269a4871a4e3a4b884e46c3e3fca89790c5940f9..00cdee9de21fffb991976cfb1b23580ee8c24922 100644
--- a/tests/standalone/io/platform_test.dart
+++ b/tests/standalone/io/platform_test.dart
@@ -24,9 +24,15 @@ test() {
   Expect.isTrue(hostname is String && hostname != "");
   var environment = Platform.environment;
   Expect.isTrue(environment is Map<String, String>);
-  Expect.isTrue(Platform.executable.contains('dart'));
   if (!Platform.isWindows) {
-    Expect.isTrue(Platform.executable.startsWith('/'));
+    Expect.isTrue(Platform.executable.endsWith('dart'));
+    Expect.isTrue(Platform.resolvedExecutable.endsWith('dart'));
+  } else {
+    Expect.isTrue(Platform.executable.endsWith('dart.exe'));
+    Expect.isTrue(Platform.resolvedExecutable.endsWith('dart.exe'));
+  }
+  if (!Platform.isWindows) {
+    Expect.isTrue(Platform.resolvedExecutable.startsWith('/'));
   } else {
     // This assumes that tests (both locally and on the bots) are
     // running off a location referred to by a drive letter. If a UNC