[dart:io] Adds ProcessInfo.{max,current}Rss. Adds OS::MaxRSS on Fuchsia.

sdk/lib/_internal/js_runtime/lib/io_patch.dart

Index: sdk/lib/_internal/js_runtime/lib/io_patch.dart
diff --git a/sdk/lib/_internal/js_runtime/lib/io_patch.dart b/sdk/lib/_internal/js_runtime/lib/io_patch.dart
index e3342f108f3f83fe1ae57bd81a5e12bad37e9fae..59aa7fff52f5b3f87b5c9250dcef697a5fec4fe3 100644
--- a/sdk/lib/_internal/js_runtime/lib/io_patch.dart
+++ b/sdk/lib/_internal/js_runtime/lib/io_patch.dart
@@ -291,6 +291,19 @@ class _ProcessUtils {
 }
 
 @patch
+class ProcessInfo {
+  @patch
+  static int get currentRss {
+    throw new UnsupportedError("ProcessInfo.currentRss");
+  }
+
+  @patch
+  static int get maxRss {
+    throw new UnsupportedError("ProcessInfo.maxRss");
+  }
+}
+
+@patch
 class Process {
   @patch
   static Future<Process> start(String executable, List<String> arguments,