Introduce LiteralsArray to hide it's implementation.

src/mips/lithium-codegen-mips.cc

Index: src/mips/lithium-codegen-mips.cc
diff --git a/src/mips/lithium-codegen-mips.cc b/src/mips/lithium-codegen-mips.cc
index 7d44fdef2ce155e178d8a5bb30507e86f0cbd9d9..bf158b4c43a9da0713a86b625d9be2e148e53f9a 100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -5414,7 +5414,7 @@ void LCodeGen::DoRegExpLiteral(LRegExpLiteral* instr) {
   // a0 = regexp literal clone.
   // a2 and t0-t2 are used as temporaries.
   int literal_offset =
-      FixedArray::OffsetOfElementAt(instr->hydrogen()->literal_index());
+      LiteralsArray::OffsetOfLiteralAt(instr->hydrogen()->literal_index());
   __ li(t3, instr->hydrogen()->literals());
   __ lw(a1, FieldMemOperand(t3, literal_offset));
   __ LoadRoot(at, Heap::kUndefinedValueRootIndex);