Revert of Remove SIMD.js from V8.

src/full-codegen/ppc/full-codegen-ppc.cc

Index: src/full-codegen/ppc/full-codegen-ppc.cc
diff --git a/src/full-codegen/ppc/full-codegen-ppc.cc b/src/full-codegen/ppc/full-codegen-ppc.cc
index 02a9878bfb69816a65335c066c4e7b6dce2984c7..69a15eec8d9910c36868ce821f32f66fca22aff9 100644
--- a/src/full-codegen/ppc/full-codegen-ppc.cc
+++ b/src/full-codegen/ppc/full-codegen-ppc.cc
@@ -2621,6 +2621,16 @@
     __ andi(r0, r4,
             Operand((1 << Map::kIsCallable) | (1 << Map::kIsUndetectable)));
     Split(eq, if_true, if_false, fall_through, cr0);
+// clang-format off
+#define SIMD128_TYPE(TYPE, Type, type, lane_count, lane_type)   \
+  } else if (String::Equals(check, factory->type##_string())) { \
+    __ JumpIfSmi(r3, if_false);                                 \
+    __ LoadP(r3, FieldMemOperand(r3, HeapObject::kMapOffset));    \
+    __ CompareRoot(r3, Heap::k##Type##MapRootIndex);            \
+    Split(eq, if_true, if_false, fall_through);
+  SIMD128_TYPES(SIMD128_TYPE)
+#undef SIMD128_TYPE
+    // clang-format on
   } else {
     if (if_false != fall_through) __ b(if_false);
   }