Fix intermittent failure in the find integration tests

After clicking the find button we need to wait for the input field to
appear before we try to type in it, but instead we were waiting for the
button to appear. However, the button is always present, so the current
`waitForSelector` call is basically a no-op, and this can cause the
integration tests to fail intermittently if we continue before the
input field is actually visible.

This appears to be due a typo first introduced in commit
d10da90 that has been copy/pasted.

This commit fixes the issue by waiting for the input field to be visible
before we continue typing in it.

Author: timvandermeij

test/integration/find_spec.mjs

@@ -41,7 +41,7 @@ describe("find bar", () => {
         pages.map(async ([browserName, page]) => {
           // Highlight all occurrences of the letter A (case insensitive).
           await page.click("#viewFindButton");
-          await page.waitForSelector("#viewFindButton", { hidden: false });
+          await page.waitForSelector("#findInput", { visible: true });
           await page.type("#findInput", "a");
           await page.click("#findHighlightAll + label");
           await page.waitForSelector(".textLayer .highlight");
@@ -101,7 +101,7 @@ describe("find bar", () => {
       await Promise.all(
         pages.map(async ([browserName, page]) => {
           await page.click("#viewFindButton");
-          await page.waitForSelector("#viewFindButton", { hidden: false });
+          await page.waitForSelector("#findInput", { visible: true });
           await page.type("#findInput", "preferences");
           await page.waitForSelector("#findInput[data-status='']");
           await page.waitForSelector(".xfaLayer .highlight");
@@ -139,7 +139,7 @@ describe("find bar", () => {
         pages.map(async ([browserName, page]) => {
           // Search for "40"
           await page.click("#viewFindButton");
-          await page.waitForSelector("#viewFindButton", { hidden: false });
+          await page.waitForSelector("#findInput", { visible: true });
           await page.type("#findInput", "40");
 
           const highlight = await page.waitForSelector(".textLayer .highlight");