[Asm.js] Prevents assignments to immutables.

test/cctest/asmjs/test-asm-typer.cc

Index: test/cctest/asmjs/test-asm-typer.cc
diff --git a/test/cctest/asmjs/test-asm-typer.cc b/test/cctest/asmjs/test-asm-typer.cc
index bf8615e00790d41fc6064a186f7e844b3b70817c..dcb778533dcf5767bb7e205420fd51fe3526c82b 100644
--- a/test/cctest/asmjs/test-asm-typer.cc
+++ b/test/cctest/asmjs/test-asm-typer.cc
@@ -1941,4 +1941,63 @@ TEST(B63099) {
   }
 }
 
+// This issue was triggered because assignments to immutable symbols (e.g., the
+// module's name, or any of the asm.js' module parameters) was not being
+// handled.
+TEST(B640194) {
+  const char* kTests[] = {
+      "function asm() {\n"
+      "  'use asm';\n"
+      "  function f() {\n"
+      "    asm = 0;\n"
+      "  }\n"
+      "  return f;\n"
+      "}",
+      "function asm(stdlib) {\n"
+      "  'use asm';\n"
+      "  function f() {\n"
+      "    stdlib = 0;\n"
+      "  }\n"
+      "  return f;\n"
+      "}",
+      "function asm(stdlib, foreign) {\n"
+      "  'use asm';\n"
+      "  function f() {\n"
+      "    foreign = 0;\n"
+      "  }\n"
+      "  return f;\n"
+      "}",
+      "function asm(stdlib, foreign, heap) {\n"
+      "  'use asm';\n"
+      "  function f() {\n"
+      "    heap = 0;\n"
+      "  }\n"
+      "  return f;\n"
+      "}",
+      "function asm(stdlib, foreign, heap) {\n"
+      "  'use asm';\n"
+      "  var f = stdlib.Math.fround;\n"
+      "  function f() {\n"
+      "    f = 0;\n"
+      "  }\n"
+      "  return f;\n"
+      "}",
+      "function asm(stdlib, foreign, heap) {\n"
+      "  'use asm';\n"
+      "  var E = stdlib.Math.E;\n"
+      "  function f() {\n"
+      "    E = 0;\n"
+      "  }\n"
+      "  return f;\n"
+      "}",
+  };
+  for (size_t ii = 0; ii < arraysize(kTests); ++ii) {
+    if (!ValidationOf(Module(kTests[ii]))
+             ->FailsWithMessage("Can't assign to immutable symbol")) {
+      std::cerr << "Test:\n" << kTests[ii];
+      CHECK(false);
+    }
+  }
+}
+
 }  // namespace