Revert of Internalize strings in-place

src/mips/codegen-mips.cc

Index: src/mips/codegen-mips.cc
diff --git a/src/mips/codegen-mips.cc b/src/mips/codegen-mips.cc
index 15011023ccdaad35a072844fad8abce5be3d9d1d..a57299abf67bc55042bc764ca7069a9a0e3cf166 100644
--- a/src/mips/codegen-mips.cc
+++ b/src/mips/codegen-mips.cc
@@ -620,10 +620,9 @@
   __ Branch(&check_sequential, eq, at, Operand(zero_reg));
 
   // Dispatch on the indirect string shape: slice or cons.
-  Label cons_string, thin_string;
-  __ And(at, result, Operand(kStringRepresentationMask));
-  __ Branch(&cons_string, eq, at, Operand(kConsStringTag));
-  __ Branch(&thin_string, eq, at, Operand(kThinStringTag));
+  Label cons_string;
+  __ And(at, result, Operand(kSlicedNotConsMask));
+  __ Branch(&cons_string, eq, at, Operand(zero_reg));
 
   // Handle slices.
   Label indirect_string_loaded;
@@ -631,11 +630,6 @@
   __ lw(string, FieldMemOperand(string, SlicedString::kParentOffset));
   __ sra(at, result, kSmiTagSize);
   __ Addu(index, index, at);
-  __ jmp(&indirect_string_loaded);
-
-  // Handle thin strings.
-  __ bind(&thin_string);
-  __ lw(string, FieldMemOperand(string, ThinString::kActualOffset));
   __ jmp(&indirect_string_loaded);
 
   // Handle cons strings.