MIPS: port Generated code for substring slices in x64 and arm.

src/mips/macro-assembler-mips.h

Index: src/mips/macro-assembler-mips.h
diff --git a/src/mips/macro-assembler-mips.h b/src/mips/macro-assembler-mips.h
index ec0b2029e4e151c5b911e67a7f2ef07e6f08aa79..f86b9b36de13b28da31baf8e8a3ab70dc5b55b24 100644
--- a/src/mips/macro-assembler-mips.h
+++ b/src/mips/macro-assembler-mips.h
@@ -362,6 +362,16 @@ class MacroAssembler: public Assembler {
                                Register scratch1,
                                Register scratch2,
                                Label* gc_required);
+  void AllocateTwoByteSlicedString(Register result,
+                                   Register length,
+                                   Register scratch1,
+                                   Register scratch2,
+                                   Label* gc_required);
+  void AllocateAsciiSlicedString(Register result,
+                                 Register length,
+                                 Register scratch1,
+                                 Register scratch2,
+                                 Label* gc_required);
 
   // Allocates a heap number or jumps to the gc_required label if the young
   // space is full and a scavenge is needed. All registers are clobbered also