Remove gen-typescript-declarations; manually add LegacyElementMixin's setAttribute type.

Author: bicknellr

gen-tsd.json

@@ -115,6 +115,13 @@ interface LegacyElementMixin extends ElementMixin, PropertyEffects, TemplateStam
    */
   created(): void;
 
+  /**
+   * Sets the value of an attribute.
+   * @param name The name of the attribute to change.
+   * @param value The new attribute value.
+   */
+  setAttribute(name: string, value: string): void;
+
   /**
    * Removes an attribute.
    *

lib/legacy/legacy-element-mixin.d.ts

@@ -145,12 +145,6 @@ export const LegacyElementMixin = dedupingMixin((base) => {
 
     /**
      * Sets the value of an attribute.
-     *
-     * NOTE: This function is explicitly excluded when running
-     * gen-typescript-declarations because the function it overrides has
-     * different signatures in Closure and TypeScript's built-in types. This
-     * function's signature should match the signature from Closure:
-     * https://github.com/google/closure-compiler/blob/8972fd4e9b0689e7ebdeea53580521c819f6aecc/externs/browser/w3c_dom1.js#L686-L694
      * @override
      * @param {string} name The name of the attribute to change.
      * @param {string|number|boolean|!TrustedHTML|!TrustedScriptURL|!TrustedURL} value The new attribute value.