Revert of Remove SIMD.js from V8.

src/code-stubs.cc

Index: src/code-stubs.cc
diff --git a/src/code-stubs.cc b/src/code-stubs.cc
index 7e5f07b6fc3566dfae7829c02f4333f9260831f4..aeb4ad307e9d1c355f41c528c76020ba4aaaf704 100644
--- a/src/code-stubs.cc
+++ b/src/code-stubs.cc
@@ -488,6 +488,21 @@
   assembler.Return(result);
 }
 
+#define SIMD128_GEN_ASM(TYPE, Type, type, lane_count, lane_type)           \
+  void Allocate##Type##Stub::GenerateAssembly(                             \
+      compiler::CodeAssemblerState* state) const {                         \
+    CodeStubAssembler assembler(state);                                    \
+    compiler::Node* result =                                               \
+        assembler.Allocate(Simd128Value::kSize, CodeStubAssembler::kNone); \
+    compiler::Node* map = assembler.LoadMap(result);                       \
+    assembler.StoreNoWriteBarrier(                                         \
+        MachineRepresentation::kTagged, map,                               \
+        assembler.HeapConstant(isolate()->factory()->type##_map()));       \
+    assembler.Return(result);                                              \
+  }
+SIMD128_TYPES(SIMD128_GEN_ASM)
+#undef SIMD128_GEN_ASM
+
 void StringLengthStub::GenerateAssembly(
     compiler::CodeAssemblerState* state) const {
   CodeStubAssembler assembler(state);
@@ -1944,6 +1959,15 @@
       Runtime::FunctionForId(Runtime::kAllocateHeapNumber)->entry);
 }
 
+
+#define SIMD128_INIT_DESC(TYPE, Type, type, lane_count, lane_type) \
+  void Allocate##Type##Stub::InitializeDescriptor(                 \
+      CodeStubDescriptor* descriptor) {                            \
+    descriptor->Initialize(                                        \
+        Runtime::FunctionForId(Runtime::kCreate##Type)->entry);    \
+  }
+SIMD128_TYPES(SIMD128_INIT_DESC)
+#undef SIMD128_INIT_DESC
 
 void ToBooleanICStub::InitializeDescriptor(CodeStubDescriptor* descriptor) {
   descriptor->Initialize(FUNCTION_ADDR(Runtime_ToBooleanIC_Miss));
@@ -2130,6 +2154,9 @@
     new_hints |= ToBooleanHint::kHeapNumber;
     double value = HeapNumber::cast(*object)->value();
     to_boolean_value = value != 0 && !std::isnan(value);
+  } else if (object->IsSimd128Value()) {
+    new_hints |= ToBooleanHint::kSimdValue;
+    to_boolean_value = true;
   } else {
     // We should never see an internal object at runtime here!
     UNREACHABLE();