[wasm] Check that type intersections don't yield empty.

test/mjsunit/wasm/asm-wasm.js

Index: test/mjsunit/wasm/asm-wasm.js
diff --git a/test/mjsunit/wasm/asm-wasm.js b/test/mjsunit/wasm/asm-wasm.js
index 54d7d7af31b47dd7c9a59adc363a19412c9246eb..4c28b619c306b9b6691e3a8e2a189a372a37de69 100644
--- a/test/mjsunit/wasm/asm-wasm.js
+++ b/test/mjsunit/wasm/asm-wasm.js
@@ -682,6 +682,7 @@ function TestModDoubleNegative() {
 
 assertWasm(28, TestModDoubleNegative);
 
+
 (function () {
 function TestNamedFunctions() {
   "use asm";
@@ -707,6 +708,7 @@ module.init();
 assertEquals(77.5, module.add());
 })();
 
+
 (function () {
 function TestGlobalsWithInit() {
   "use asm";
@@ -1358,6 +1360,38 @@ assertWasm(1, TestXor);
 })();
 
 
+(function TestBadAssignDoubleFromIntish() {
+  function Module(stdlib, foreign, heap) {
+    "use asm";
+    function func() {
+      var a = 1;
+      var b = 3.0;
+      b = a;
+    }
+    return {func: func};
+  }
+  assertThrows(function() {
+    Wasm.instantiateModuleFromAsm(Module.toString());
+  });
+})();
+
+
+(function TestBadAssignIntFromDouble() {
+  function Module(stdlib, foreign, heap) {
+    "use asm";
+    function func() {
+      var a = 1;
+      var b = 3.0;
+      a = b;
+    }
+    return {func: func};
+  }
+  assertThrows(function() {
+    Wasm.instantiateModuleFromAsm(Module.toString());
+  });
+})();
+
+
 (function TestBadMultiplyIntish() {
   function Module(stdlib, foreign, heap) {
     "use asm";