JS backend: report expression location on error in StringTemplateTranslator.

(cherry picked from commit a2765d3)

js/js.translator/testFiles/expression/stringTemplates/cases/stringValues.kt

@@ -1,5 +1,10 @@
 package foo
 
+// test String template must have one or more entries.
+public class Fe {
+  fun open(method:String, url: String, async: Boolean = true, user: String = "", password: String = "") = "$method $url $async $user $password"
+}
+
 fun box(): Boolean {
     val a = "abc"
     val b = "def"
@@ -10,5 +15,5 @@ fun box(): Boolean {
     val v1 = null
     if ("returns null null" != "returns $v1 ${null}") return false
 
-    return true
+    return Fe().open("22", "33") == "22 33 true  "
 }