Add exception handler cache to isolate

runtime/vm/exceptions.h

Index: runtime/vm/exceptions.h
diff --git a/runtime/vm/exceptions.h b/runtime/vm/exceptions.h
index 48e0f4afbc01defc6a6467d0a135a2d6570a0866..2d80881e26402b22e1a07da755dbc24f1f8d41a1 100644
--- a/runtime/vm/exceptions.h
+++ b/runtime/vm/exceptions.h
@@ -90,6 +90,15 @@ class Exceptions : AllStatic {
   DISALLOW_COPY_AND_ASSIGN(Exceptions);
 };
 
+// The index into the ExceptionHandlers table corresponds to
+// the try_index of the handler.
+struct HandlerInfo {
+  uint32_t handler_pc_offset;  // PC offset value of handler.
+  int16_t outer_try_index;     // Try block index of enclosing try block.
+  int8_t needs_stacktrace;     // True if a stacktrace is needed.
+  int8_t has_catch_all;        // Catches all exceptions.
+};
+
 }  // namespace dart
 
 #endif  // RUNTIME_VM_EXCEPTIONS_H_