Add error handling to random access file

runtime/bin/dartutils.cc

Index: runtime/bin/dartutils.cc
diff --git a/runtime/bin/dartutils.cc b/runtime/bin/dartutils.cc
index 410138630582bbcc206ab004a7308f1afe4b512e..baeb8c5ff0a240919767cc3667d74e02ee093d49 100644
--- a/runtime/bin/dartutils.cc
+++ b/runtime/bin/dartutils.cc
@@ -409,6 +409,7 @@ Dart_CObject* CObject::NewByteArray(int length) {
 
 static int kIllegalArgumentError = 1;
 static int kOSError = 2;
+static int kFileClosedError = 3;
 
 
 CObject* CObject::IllegalArgumentError() {
@@ -418,6 +419,13 @@ CObject* CObject::IllegalArgumentError() {
 }
 
 
+CObject* CObject::FileClosedError() {
+  CObjectArray* result = new CObjectArray(CObject::NewArray(1));
+  result->SetAt(0, new CObjectInt32(CObject::NewInt32(kFileClosedError)));
+  return result;
+}
+
+
 CObject* CObject::NewOSError() {
   OSError os_error;
   return NewOSError(&os_error);