Revert of Remove SIMD.js from V8.

src/crankshaft/mips/lithium-codegen-mips.cc

Index: src/crankshaft/mips/lithium-codegen-mips.cc
diff --git a/src/crankshaft/mips/lithium-codegen-mips.cc b/src/crankshaft/mips/lithium-codegen-mips.cc
index 6e03e46bd59f430fa7d2bdeb60c11f2984fabf98..20893e5aa268d278702886211b95bd3a80cbe47c 100644
--- a/src/crankshaft/mips/lithium-codegen-mips.cc
+++ b/src/crankshaft/mips/lithium-codegen-mips.cc
@@ -2025,6 +2025,14 @@
         __ Branch(instr->TrueLabel(chunk_), eq, scratch, Operand(SYMBOL_TYPE));
       }
 
+      if (expected & ToBooleanHint::kSimdValue) {
+        // SIMD value -> true.
+        const Register scratch = scratch1();
+        __ lbu(scratch, FieldMemOperand(map, Map::kInstanceTypeOffset));
+        __ Branch(instr->TrueLabel(chunk_), eq, scratch,
+                  Operand(SIMD128_VALUE_TYPE));
+      }
+
       if (expected & ToBooleanHint::kHeapNumber) {
         // heap number -> false iff +0, -0, or NaN.
         DoubleRegister dbl_scratch = double_scratch0();
@@ -5162,6 +5170,19 @@
     *cmp2 = Operand(zero_reg);
     final_branch_condition = eq;
 
+// clang-format off
+#define SIMD128_TYPE(TYPE, Type, type, lane_count, lane_type)        \
+  } else if (String::Equals(type_name, factory->type##_string())) {  \
+    __ JumpIfSmi(input, false_label);                                \
+    __ lw(input, FieldMemOperand(input, HeapObject::kMapOffset));    \
+    __ LoadRoot(at, Heap::k##Type##MapRootIndex);                    \
+    *cmp1 = input;                                                   \
+    *cmp2 = Operand(at);                                             \
+    final_branch_condition = eq;
+  SIMD128_TYPES(SIMD128_TYPE)
+#undef SIMD128_TYPE
+    // clang-format on
+
   } else {
     *cmp1 = at;
     *cmp2 = Operand(zero_reg);  // Set to valid regs, to avoid caller assertion.