Only reload libraries when they may have been modified.

runtime/vm/snapshot_test.cc

Index: runtime/vm/snapshot_test.cc
diff --git a/runtime/vm/snapshot_test.cc b/runtime/vm/snapshot_test.cc
index bcd69f7b6527a8620b19d81be4e5769f023b4e52..915358a6a1c154f55e8f304bbb219d3d5616b3d6 100644
--- a/runtime/vm/snapshot_test.cc
+++ b/runtime/vm/snapshot_test.cc
@@ -1373,6 +1373,7 @@ UNIT_TEST_CASE(ScriptSnapshot) {
 
     // Load the library.
     Dart_Handle import_lib = Dart_LoadLibrary(NewString("dart_import_lib"),
+                                              Dart_Null(),
                                               NewString(kLibScriptChars),
                                               0, 0);
     EXPECT_VALID(import_lib);
@@ -1435,6 +1436,7 @@ UNIT_TEST_CASE(ScriptSnapshot) {
 
     // Load the library.
     Dart_Handle lib = Dart_LoadLibrary(NewString("dart_lib"),
+                                       Dart_Null(),
                                        NewString(kScriptChars),
                                        0, 0);
     EXPECT_VALID(lib);
@@ -1610,6 +1612,7 @@ UNIT_TEST_CASE(ScriptSnapshot2) {
 
     // Load the library.
     Dart_Handle import_lib = Dart_LoadLibrary(NewString("dart_import_lib"),
+                                              Dart_Null(),
                                               NewString(kLibScriptChars),
                                               0, 0);
     EXPECT_VALID(import_lib);