Add support for compression filters in the mojo dart:io

mojo/dart/embedder/common.h

Index: mojo/dart/embedder/common.h
diff --git a/mojo/dart/embedder/common.h b/mojo/dart/embedder/common.h
index 526c04802bb0ca606c6b381941ba88356075df90..136708dac0b423dd3aca7f551afca572d6bdaffb 100644
--- a/mojo/dart/embedder/common.h
+++ b/mojo/dart/embedder/common.h
@@ -12,6 +12,15 @@ namespace dart {
 
 class DartEmbedder {
  public:
+  static Dart_Handle GetDartType(const char* library_url,
+                                 const char* class_name);
+
+  static Dart_Handle NewDartExceptionWithMessage(const char* library_url,
+                                                 const char* error_type,
+                                                 const char* message);
+
+  static Dart_Handle NewInternalError(const char* message);
+
   // Returns the integer value of a Dart object. If the object is not
   // an integer value an API error is propagated.
   static int64_t GetIntegerValue(Dart_Handle value_obj);