fix corner case in templates (#4607)

fixes #4606

lib/compress.js

@@ -9956,7 +9956,9 @@ merge(Compressor.prototype, {
                 var node = exprs[i];
                 var ev = node.evaluate(compressor);
                 if (ev === node) continue;
-                ev = "" + ev;
+                ev = ("" + ev).replace(/\r|\\|`/g, function(s) {
+                    return "\\" + (s == "\r" ? "r" : s);
+                });
                 if (ev.length > node.print_to_string().length + 3) continue;
                 exprs.splice(i, 1);
                 strs.splice(i, 2, strs[i] + ev + strs[i + 1]);

test/compress/templates.js

@@ -222,3 +222,18 @@ issue_4604: {
     expect_stdout: "PASS"
     node_version: ">=4"
 }
+
+issue_4606: {
+    options = {
+        evaluate: true,
+        templates: true,
+    }
+    input: {
+        console.log(`${typeof A} ${"\r"} ${"\\"} ${"`"}`);
+    }
+    expect: {
+        console.log(`${typeof A} \r \\ \``);
+    }
+    expect_stdout: "undefined \r \\ `"
+    node_version: ">=4"
+}