Add Float64x2, Float64x2List, etc... with runtime and dart2js implementations

runtime/platform/globals.h

Index: runtime/platform/globals.h
diff --git a/runtime/platform/globals.h b/runtime/platform/globals.h
index 9e27506dd2b77ee001cd26958b8115a8b7753345..ef7cd0178906b06745073455271decf57dc8d4e0 100644
--- a/runtime/platform/globals.h
+++ b/runtime/platform/globals.h
@@ -89,6 +89,14 @@ struct simd128_value_t {
     storage[3] = vv[3];
     return *this;
   }
+  simd128_value_t& readFrom(const double* v) {
+    const float* vv = reinterpret_cast<const float*>(v);
+    storage[0] = vv[0];
+    storage[1] = vv[1];
+    storage[2] = vv[2];
+    storage[3] = vv[3];
+    return *this;
+  }
   simd128_value_t& readFrom(const simd128_value_t* v) {
     *this = *v;
     return *this;
@@ -106,6 +114,13 @@ struct simd128_value_t {
     vv[2] = storage[2];
     vv[3] = storage[3];
   }
+  void writeTo(double* v) {
+    float* vv = reinterpret_cast<float*>(v);
+    vv[0] = storage[0];
+    vv[1] = storage[1];
+    vv[2] = storage[2];
+    vv[3] = storage[3];
+  }
   void writeTo(simd128_value_t* v) {
     *v = *this;
   }