[wasm][asm.js] Check that property keys are literals for imports.

BUG=672785
R=titzer@chromium.org

Review-Url: https://codereview.chromium.org/2566683002
Cr-Commit-Position: refs/heads/master@{#41624}

src/asmjs/asm-typer.cc

@@ -335,6 +335,9 @@ void AsmTyper::InitializeStdlib() {
 AsmTyper::VariableInfo* AsmTyper::ImportLookup(Property* import) {
   auto* obj = import->obj();
   auto* key = import->key()->AsLiteral();
+  if (key == nullptr) {
+    return nullptr;
+  }
 
   ObjectTypeMap* stdlib = &stdlib_types_;
   if (auto* obj_as_property = obj->AsProperty()) {

test/mjsunit/asm/asm-validation.js

@@ -316,6 +316,17 @@ function assertValidAsm(func) {
   assertEquals(3, m.foo(3));
 })();
 
+(function TestBadImport() {
+  function Module(stdlib) {
+    "use asm";
+    var set = 0;
+    var foo = stdlib[set];
+    return {};
+  }
+  var m = Module(this);
+  assertFalse(%IsAsmWasmCode(Module));
+})();
+
 (function TestBadishBooleanExprAnnotation() {
   function Module() {
     "use asm";