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

runtime/bin/process_unsupported.cc

Index: runtime/bin/process_unsupported.cc
diff --git a/runtime/bin/process_unsupported.cc b/runtime/bin/process_unsupported.cc
index 1bb4ce879c8cb5f92616a8b1bf31b46a20e88ac4..f73f82d210ecad0a3b88cd7c789b5336364b7db8 100644
--- a/runtime/bin/process_unsupported.cc
+++ b/runtime/bin/process_unsupported.cc
@@ -92,6 +92,18 @@ void FUNCTION_NAME(StringToSystemEncoding)(Dart_NativeArguments args) {
       DartUtils::NewInternalError("Process is not supported on this platform"));
 }
 
+
+void FUNCTION_NAME(ProcessInfo_CurrentRSS)(Dart_NativeArguments args) {
+  Dart_ThrowException(
+      DartUtils::NewInternalError("Process is not supported on this platform"));
+}
+
+
+void FUNCTION_NAME(ProcessInfo_MaxRSS)(Dart_NativeArguments args) {
+  Dart_ThrowException(
+      DartUtils::NewInternalError("Process is not supported on this platform"));
+}
+
 }  // namespace bin
 }  // namespace dart