VM: Fix build on GCC which requires explicit initialization of the base class

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
diff --git a/runtime/vm/intermediate_language.h b/runtime/vm/intermediate_language.h
index 9203787ef65f079fe65fbdb7615ce37449a2a944..65a16c6eac5bdeba6dcc949d68e309c4ca0a9e58 100644
--- a/runtime/vm/intermediate_language.h
+++ b/runtime/vm/intermediate_language.h
@@ -56,7 +56,8 @@ class CompileType : public ZoneAllocated {
       : is_nullable_(is_nullable), cid_(cid), type_(type) {}
 
   CompileType(const CompileType& other)
-      : is_nullable_(other.is_nullable_),
+      : ZoneAllocated(),
+        is_nullable_(other.is_nullable_),
         cid_(other.cid_),
         type_(other.type_) {}