[regexp] correctly advance zero length matches for global/unicode.

src/regexp/mips/regexp-macro-assembler-mips.cc

Index: src/regexp/mips/regexp-macro-assembler-mips.cc
diff --git a/src/regexp/mips/regexp-macro-assembler-mips.cc b/src/regexp/mips/regexp-macro-assembler-mips.cc
index 9c59328ed122668afe229f72f86854ffe855f66e..64e35c0f3e328a89c6b6dc51e0c48e013c2455b9 100644
--- a/src/regexp/mips/regexp-macro-assembler-mips.cc
+++ b/src/regexp/mips/regexp-macro-assembler-mips.cc
@@ -801,9 +801,12 @@ Handle<HeapObject> RegExpMacroAssemblerMIPS::GetCode(Handle<String> source) {
           __ Branch(&exit_label_, eq, current_input_offset(),
                     Operand(zero_reg));
           // Advance current position after a zero-length match.
+          Label advance;
+          __ bind(&advance);
           __ Addu(current_input_offset(),
                   current_input_offset(),
                   Operand((mode_ == UC16) ? 2 : 1));
+          if (global_unicode()) CheckNotInSurrogatePair(0, &advance);
         }
 
         __ Branch(&load_char_start_regexp);