[Interpreter] Ensure we always have an outer register allocation scope.

test/cctest/interpreter/test-interpreter.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/execution.h"
 #include "src/handles.h"
 #include "src/interpreter/bytecode-array-builder.h"
 #include "src/interpreter/interpreter.h"
@@ skipping 2213 matching lines @@
       std::make_pair("var a = { val: 11 }; return ++a.val;",
                      handle(Smi::FromInt(12), isolate)),
       std::make_pair("var name = 'val'; var a = { val: 22 }; return --a[name];",
                      handle(Smi::FromInt(21), isolate)),
       std::make_pair("var name = 'val'; var a = { val: 22 }; return a[name]++;",
                      handle(Smi::FromInt(22), isolate)),
       std::make_pair("var a = 1; (function() { a = 2 })(); return ++a;",
                      handle(Smi::FromInt(3), isolate)),
       std::make_pair("var a = 1; (function() { a = 2 })(); return a--;",
                      handle(Smi::FromInt(2), isolate)),
+      std::make_pair("var i = 5; while(i--) {}; return i;",
+                     handle(Smi::FromInt(-1), isolate)),
+      std::make_pair("var i = 1; if(i--) { return 1; } else { return 2; };",
+                     handle(Smi::FromInt(1), isolate)),
+      std::make_pair("var i = -2; do {} while(i++) {}; return i;",
+                      handle(Smi::FromInt(1), isolate)),
+      std::make_pair("var i = -1; for(; i++; ) {}; return i",
+                      handle(Smi::FromInt(1), isolate)),
+      std::make_pair("var i = 20; switch(i++) {\n"
+                     "  case 20: return 1;\n"
+                     "  default: return 2;\n"
+                     "}",
+                     handle(Smi::FromInt(1), isolate)),
   };
 
   for (size_t i = 0; i < arraysize(count_ops); i++) {
     std::string source(InterpreterTester::SourceForBody(count_ops[i].first));
     InterpreterTester tester(handles.main_isolate(), source.c_str());
     auto callable = tester.GetCallable<>();
 
     Handle<i::Object> return_value = callable().ToHandleChecked();
     CHECK(return_value->SameValue(*count_ops[i].second));
   }
@@ skipping 1301 matching lines @@
     auto callable = tester.GetCallable<>();
 
     Handle<i::Object> return_value = callable().ToHandleChecked();
     CHECK(return_value->SameValue(*eval_global[i].second));
   }
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8