X87: Fix assertion in full codegen for holed 'this'

port 275e088a (r26423)

original commit message:

BUG=
R=weiliang.lin@intel.com

Review URL: https://codereview.chromium.org/907853002

Cr-Commit-Position: refs/heads/master@{#26519}

src/x87/full-codegen-x87.cc

@@ -1451,7 +1451,8 @@ void FullCodeGenerator::EmitVariableLoad(VariableProxy* proxy) {
         if (var->scope()->DeclarationScope() != scope()->DeclarationScope()) {
           skip_init_check = false;
         } else if (var->is_this()) {
-          CHECK((info_->shared_info()->kind() & kSubclassConstructor) != 0);
+          CHECK(info_->function() != nullptr &&
+                (info_->function()->kind() & kSubclassConstructor) != 0);
           // TODO(dslomov): implement 'this' hole check elimination.
           skip_init_check = false;
         } else {