Fix StoreIndexedInstr input representation requirements for Int32/Uint32 arrays.

runtime/vm/assembler_mips.h

Index: runtime/vm/assembler_mips.h
diff --git a/runtime/vm/assembler_mips.h b/runtime/vm/assembler_mips.h
index fbc52dc2031c0cf8bc35b788aa25989915ef4823..46219dda9ed25de3d7bdfcbdc57cebcecec64e1a 100644
--- a/runtime/vm/assembler_mips.h
+++ b/runtime/vm/assembler_mips.h
@@ -856,7 +856,9 @@ class Assembler : public ValueObject {
       const uint16_t low = Utils::Low16Bits(value);
       const uint16_t high = Utils::High16Bits(value);
       lui(rd, Immediate(high));
-      ori(rd, rd, Immediate(low));
+      if (low != 0) {
+        ori(rd, rd, Immediate(low));
+      }
     }
   }
 
@@ -1125,6 +1127,10 @@ class Assembler : public ValueObject {
     sll(reg, reg, kSmiTagSize);
   }
 
+  void SmiTag(Register dst, Register src) {
+    sll(dst, src, kSmiTagSize);
+  }
+
   void SmiUntag(Register reg) {
     sra(reg, reg, kSmiTagSize);
   }