Add new Float32x4 type for SIMD.js.

src/globals.h

Index: src/globals.h
diff --git a/src/globals.h b/src/globals.h
index c73f395cb6808672ffc19863112facb8c32c4752..218535cde3c4e2900fee1ad64e57a058bdf20198 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -124,6 +124,7 @@ const int kShortSize     = sizeof(short);     // NOLINT
 const int kIntSize       = sizeof(int);       // NOLINT
 const int kInt32Size     = sizeof(int32_t);   // NOLINT
 const int kInt64Size     = sizeof(int64_t);   // NOLINT
+const int kFloatSize     = sizeof(float);     // NOLINT
 const int kDoubleSize    = sizeof(double);    // NOLINT
 const int kIntptrSize    = sizeof(intptr_t);  // NOLINT
 const int kPointerSize   = sizeof(void*);     // NOLINT