[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 8cb0d9cf5a85ea8f028e93ed9a4700bf5846f6d7..9f924fc1b6f00b4f47186917afdca9c11b57d59c 100644
--- a/src/regexp/mips/regexp-macro-assembler-mips.cc
+++ b/src/regexp/mips/regexp-macro-assembler-mips.cc
@@ -808,9 +808,12 @@ 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);