Expose SIMD.Float32x4 type to Javascript.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 6f858653eab77292251ece5933e95b6e97faa691..c73bcfc1977e2cb8426b9ef521232aaded755a0f 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -2208,6 +2208,12 @@ void LCodeGen::DoBranch(LBranch* instr) {
         __ j(equal, instr->TrueLabel(chunk_));
       }
 
+      if (expected.Contains(ToBooleanStub::SIMD_TYPE)) {
+        // SIMD value -> true.
+        __ CmpInstanceType(map, FLOAT32X4_TYPE);
+        __ j(equal, instr->TrueLabel(chunk_));
+      }
+
       if (expected.Contains(ToBooleanStub::HEAP_NUMBER)) {
         // heap number -> false iff +0, -0, or NaN.
         Label not_heap_number;
@@ -5709,6 +5715,11 @@ Condition LCodeGen::EmitTypeofIs(LTypeofIsAndBranch* instr, Register input) {
              Immediate(1 << Map::kIsUndetectable));
     final_branch_condition = zero;
 
+  } else if (String::Equals(type_name, factory->float32x4_string())) {
+    __ JumpIfSmi(input, false_label, false_distance);
+    __ CmpObjectType(input, FLOAT32X4_TYPE, input);
+    final_branch_condition = equal;
+
   } else {
     __ jmp(false_label, false_distance);
   }