Use regular map-checks to guard string-length loading.

src/mips/stub-cache-mips.cc

Index: src/mips/stub-cache-mips.cc
diff --git a/src/mips/stub-cache-mips.cc b/src/mips/stub-cache-mips.cc
index 58452cad1b9902f24dcb5c104afa58da371094ee..97bd87202e456faf65aafb01f82efc1b5ef232fa 100644
--- a/src/mips/stub-cache-mips.cc
+++ b/src/mips/stub-cache-mips.cc
@@ -374,30 +374,26 @@ void StubCompiler::GenerateLoadStringLength(MacroAssembler* masm,
                                             Register receiver,
                                             Register scratch1,
                                             Register scratch2,
-                                            Label* miss,
-                                            bool support_wrappers) {
+                                            Label* miss) {
   Label check_wrapper;
 
   // Check if the object is a string leaving the instance type in the
   // scratch1 register.
-  GenerateStringCheck(masm, receiver, scratch1, scratch2, miss,
-                      support_wrappers ? &check_wrapper : miss);
+  GenerateStringCheck(masm, receiver, scratch1, scratch2, miss, &check_wrapper);
 
   // Load length directly from the string.
   __ Ret(USE_DELAY_SLOT);
   __ lw(v0, FieldMemOperand(receiver, String::kLengthOffset));
 
-  if (support_wrappers) {
-    // Check if the object is a JSValue wrapper.
-    __ bind(&check_wrapper);
-    __ Branch(miss, ne, scratch1, Operand(JS_VALUE_TYPE));
+  // Check if the object is a JSValue wrapper.
+  __ bind(&check_wrapper);
+  __ Branch(miss, ne, scratch1, Operand(JS_VALUE_TYPE));
 
-    // Unwrap the value and check if the wrapped value is a string.
-    __ lw(scratch1, FieldMemOperand(receiver, JSValue::kValueOffset));
-    GenerateStringCheck(masm, scratch1, scratch2, scratch2, miss, miss);
-    __ Ret(USE_DELAY_SLOT);
-    __ lw(v0, FieldMemOperand(scratch1, String::kLengthOffset));
-  }
+  // Unwrap the value and check if the wrapped value is a string.
+  __ lw(scratch1, FieldMemOperand(receiver, JSValue::kValueOffset));
+  GenerateStringCheck(masm, scratch1, scratch2, scratch2, miss, miss);
+  __ Ret(USE_DELAY_SLOT);
+  __ lw(v0, FieldMemOperand(scratch1, String::kLengthOffset));
 }