[stubs] Introduce a proper ToBooleanStub.

src/compiler/linkage.cc

 // Copyright 2014 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/ast/scopes.h"
 #include "src/code-stubs.h"
 #include "src/compiler.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/frame.h"
 #include "src/compiler/linkage.h"
@@ skipping 382 matching lines @@
   return new (zone) CallDescriptor(     // --
       CallDescriptor::kCallCodeObject,  // kind
       target_type,                      // target MachineType
       target_loc,                       // target location
       types.Build(),                    // machine_sig
       locations.Build(),                // location_sig
       stack_parameter_count,            // stack_parameter_count
       properties,                       // properties
       kNoCalleeSaved,                   // callee-saved registers
       kNoCalleeSaved,                   // callee-saved fp
-      flags,                            // flags
+      CallDescriptor::kCanUseRoots |    // flags
+          flags,                        // flags
       descriptor.DebugName(isolate));
 }
 
 
 LinkageLocation Linkage::GetOsrValueLocation(int index) const {
   CHECK(incoming_->IsJSFunctionCall());
   int parameter_count = static_cast<int>(incoming_->JSParameterCount() - 1);
   int first_stack_slot = OsrHelper::FirstStackSlotIndex(parameter_count);
 
   if (index == kOsrContextSpillSlotIndex) {
@@ skipping 31 matching lines @@
   } else {
     DCHECK(loc == regloc(kContextRegister));
     return LinkageLocation::ForCalleeFrameSlot(Frame::kContextSlot);
   }
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8