template-literals: remove unnecessary strings, only add "" to beginning if second node isn't a string - fixes #1732

test/core/fixtures/transformation/es6.template-literals/expression-first/actual.js

@@ -0,0 +1,8 @@
+const foo = 5;
+const bar = 10;
+const baz = 15;
+
+const example = `${"a"}`;
+const example2 = `${1}`;
+const example3 = 1 + `${foo}${bar}${baz}`;
+const example4 = 1 + `${foo}bar${baz}`;

test/core/fixtures/transformation/es6.template-literals/expression-first/expected.js

@@ -0,0 +1,10 @@
+"use strict";
+
+var foo = 5;
+var bar = 10;
+var baz = 15;
+
+var example = "a";
+var example2 = "" + 1;
+var example3 = 1 + ("" + foo + bar + baz);
+var example4 = 1 + (foo + "bar" + baz);