JS backend: report diagnostic for class literal(Foo::class) instead of crash with Exception.

compiler/testData/cli/js/diagnosticForClassLiteral.args

@@ -0,0 +1,4 @@
+$TESTDATA_DIR$/diagnosticForClassLiteral.kt
+-no-stdlib
+-output
+$TEMP_DIR$/out.js

compiler/testData/cli/js/diagnosticForClassLiteral.kt

@@ -0,0 +1,7 @@
+package foo
+
+class A
+
+fun test() {
+    A::class
+}

compiler/testData/cli/js/diagnosticForClassLiteral.out

@@ -0,0 +1,3 @@
+WARNING: compiler/testData/cli/js/diagnosticForClassLiteral.kt: (6, 5) The expression is unused
+ERROR: compiler/testData/cli/js/diagnosticForClassLiteral.kt: (6, 6) Reflection types can't be loaded. Please ensure that you have Kotlin Runtime in your classpath
+COMPILATION_ERROR