Turbofan: Modify WASM linkage to store floats using only 4 bytes.

test/cctest/compiler/test-run-native-calls.cc

Index: test/cctest/compiler/test-run-native-calls.cc
diff --git a/test/cctest/compiler/test-run-native-calls.cc b/test/cctest/compiler/test-run-native-calls.cc
index a63cc8ab391f246d3e04ebc9799c2da0b97ab3cd..0a395ea1e2ec87d33c6e742f3f6b3f69fd3d4510 100644
--- a/test/cctest/compiler/test-run-native-calls.cc
+++ b/test/cctest/compiler/test-run-native-calls.cc
@@ -154,10 +154,7 @@ struct Allocator {
     }
   }
   int StackWords(MachineType type) {
-    // TODO(titzer): hack. float32 occupies 8 bytes on stack.
-    int size = IsFloatingPoint(type.representation())
-                   ? kDoubleSize
-                   : (1 << ElementSizeLog2Of(type.representation()));
+    int size = 1 << ElementSizeLog2Of(type.representation());
     return size <= kPointerSize ? 1 : size / kPointerSize;
   }
   void Reset() {