Add exception handler cache to isolate

runtime/vm/isolate.h

Index: runtime/vm/isolate.h
diff --git a/runtime/vm/isolate.h b/runtime/vm/isolate.h
index 4180ccee69cd841cc4e768be90334f7ae629d26f..f88bbf21263c1e9455ea5aa7d180f19c2309c69b 100644
--- a/runtime/vm/isolate.h
+++ b/runtime/vm/isolate.h
@@ -10,6 +10,8 @@
 #include "vm/atomic.h"
 #include "vm/base_isolate.h"
 #include "vm/class_table.h"
+#include "vm/exceptions.h"
+#include "vm/fixed_cache.h"
 #include "vm/handles.h"
 #include "vm/megamorphic_cache_table.h"
 #include "vm/metrics.h"
@@ -124,6 +126,10 @@ class NoReloadScope : public StackResource {
 };
 
 
+// Fixed cache for exception handler lookup.
+typedef FixedCache<intptr_t, HandlerInfo, 16> HandlerInfoCache;
+
+
 class Isolate : public BaseIsolate {
  public:
   // Keep both these enums in sync with isolate_patch.dart.
@@ -642,6 +648,8 @@ class Isolate : public BaseIsolate {
     return reload_every_n_stack_overflow_checks_;
   }
 
+  HandlerInfoCache* handler_info_cache() { return &handler_info_cache_; }
+
   void MaybeIncreaseReloadEveryNStackOverflowChecks();
 
  private:
@@ -836,6 +844,8 @@ class Isolate : public BaseIsolate {
   // Should we pause in the debug message loop after this request?
   bool should_pause_post_service_request_;
 
+  HandlerInfoCache handler_info_cache_;
+
   static Dart_IsolateCreateCallback create_callback_;
   static Dart_IsolateShutdownCallback shutdown_callback_;