VM: Make use_osr an Isolate flag, similar to how we made use_field_guards.

runtime/vm/dart.cc

Index: runtime/vm/dart.cc
diff --git a/runtime/vm/dart.cc b/runtime/vm/dart.cc
index 5a6a1b9fa3b8f138895727ab498b36c1871cc9b4..4c4a87d1438ff7132f882c6d467a78f0fd3122f1 100644
--- a/runtime/vm/dart.cc
+++ b/runtime/vm/dart.cc
@@ -669,15 +669,13 @@ const char* Dart::FeaturesString(Isolate* isolate, Snapshot::Kind kind) {
 
   if (Snapshot::IncludesCode(kind)) {
     // Checked mode affects deopt ids.
-    const bool asserts =
-        (isolate != NULL) ? isolate->asserts() : FLAG_enable_asserts;
-    const bool type_checks =
-        (isolate != NULL) ? isolate->type_checks() : FLAG_enable_type_checks;
-    const bool field_guards =
-        (isolate != NULL) ? isolate->use_field_guards() : FLAG_use_field_guards;
-    buffer.AddString(asserts ? " asserts" : " no-asserts");
-    buffer.AddString(type_checks ? " type-checks" : " no-type-checks");
-    buffer.AddString(field_guards ? "field-guards" : "no-field-guards");
+#define ADD_FLAG(name, isolate_flag, flag)                                     \
+  do {                                                                         \
+    const bool name = (isolate != NULL) ? isolate->name() : flag;              \
+    buffer.AddString(name ? (" " #name) : (" no-" #name));                     \
+  } while (0);
+    ISOLATE_FLAG_LIST(ADD_FLAG);

[rmacnak, 2017/03/03 17:45:15]

The snapshot should still work even if FLAG_error_on_bad_type or
FLAG_error_on_bad_override change, but it is safer to just include all the
isolate flags.

+#undef ADD_FLAG
 
 // Generated code must match the host architecture and ABI.
 #if defined(TARGET_ARCH_ARM)