Check for empty repetitions.

src/regexp-macro-assembler-irregexp.cc

Index: src/regexp-macro-assembler-irregexp.cc
diff --git a/src/regexp-macro-assembler-irregexp.cc b/src/regexp-macro-assembler-irregexp.cc
index cfcae325a6fe17c59da0dac8c9cfde8c7d2fa334..e2bed27ee40b1e4523a89e120904b3f3b9468da4 100644
--- a/src/regexp-macro-assembler-irregexp.cc
+++ b/src/regexp-macro-assembler-irregexp.cc
@@ -401,6 +401,14 @@ void RegExpMacroAssemblerIrregexp::IfRegisterGE(int register_index,
 }
 
 
+void RegExpMacroAssemblerIrregexp::IfRegisterEqPos(int register_index,
+                                                   Label* on_eq) {
+  Emit(BC_CHECK_REGISTER_EQ_POS);
+  Emit(register_index);
+  EmitOrLink(on_eq);
+}
+
+
 Handle<Object> RegExpMacroAssemblerIrregexp::GetCode(Handle<String> source) {
   Bind(&backtrack_);
   Emit(BC_POP_BT);