[es6] Reintroduce the instanceof operator in the backends.

src/ia32/interface-descriptors-ia32.cc

Index: src/ia32/interface-descriptors-ia32.cc
diff --git a/src/ia32/interface-descriptors-ia32.cc b/src/ia32/interface-descriptors-ia32.cc
index b8df8925ff6dfee5db56eb98558dabaa19d37d5b..8a877b1a820ec6027acbf87617591c583a34e78b 100644
--- a/src/ia32/interface-descriptors-ia32.cc
+++ b/src/ia32/interface-descriptors-ia32.cc
@@ -51,10 +51,6 @@ const Register StoreGlobalViaContextDescriptor::SlotRegister() { return ebx; }
 const Register StoreGlobalViaContextDescriptor::ValueRegister() { return eax; }
 
 
-const Register InstanceOfDescriptor::LeftRegister() { return edx; }
-const Register InstanceOfDescriptor::RightRegister() { return eax; }
-
-
 const Register StringCompareDescriptor::LeftRegister() { return edx; }
 const Register StringCompareDescriptor::RightRegister() { return eax; }