Expose SIMD.Float32x4 type to Javascript.

src/mips64/lithium-codegen-mips64.cc

Index: src/mips64/lithium-codegen-mips64.cc
diff --git a/src/mips64/lithium-codegen-mips64.cc b/src/mips64/lithium-codegen-mips64.cc
index c860606bbd40b62e43c1bed6b62646f0094cf873..d8f0ee07059da38e74f4426d8525debcfe10e94c 100644
--- a/src/mips64/lithium-codegen-mips64.cc
+++ b/src/mips64/lithium-codegen-mips64.cc
@@ -2282,6 +2282,14 @@ void LCodeGen::DoBranch(LBranch* instr) {
         __ Branch(instr->TrueLabel(chunk_), eq, scratch, Operand(SYMBOL_TYPE));
       }
 
+      if (expected.Contains(ToBooleanStub::SIMD_VALUE)) {
+        // Symbol value -> true.
+        const Register scratch = scratch1();
+        __ lbu(scratch, FieldMemOperand(map, Map::kInstanceTypeOffset));
+        __ Branch(instr->TrueLabel(chunk_), eq, scratch,
+                  Operand(FLOAT32X4_TYPE));
+      }
+
       if (expected.Contains(ToBooleanStub::HEAP_NUMBER)) {
         // heap number -> false iff +0, -0, or NaN.
         DoubleRegister dbl_scratch = double_scratch0();