Bug 1752737 - [devtools] Wait for original.js to be available before assertion r=nchevobbe

Differential Revision: https://phabricator.services.mozilla.com/D137511

devtools/client/debugger/test/mochitest/browser_dbg-breakable-lines.js

@@ -15,9 +15,9 @@ add_task(async function testBreakableLinesOverReloads() {
   info("Assert breakable lines of the first original source file, original.js");
   await waitForSource(dbg, "original.js");
   // The length of original.js is longer than the test file
-  // because the sourcemap replaces the content or the original file
+  // because the sourcemap replaces the content of the original file
   // and appends a few lines with a "WEBPACK FOOTER" comment
-  // All the appended line are empty lines or comments, so none of them are breakable.
+  // All the appended lines are empty lines or comments, so none of them are breakable.
   await assertBreakableLines(dbg, "original.js", 13, [[1,3], [5,8]]);
 
   info("Assert breakable lines of the simple first load of script.js");
@@ -29,7 +29,7 @@ add_task(async function testBreakableLinesOverReloads() {
 
   info("Wait for script.js to be ready");
   await waitForSelectedSource(dbg, "script.js");
- 
+
   info("Assert breakable lines of the more complex second load of script.js");
   await assertBreakableLines(dbg, "script.js", 23, [[2], [13,23]]);
 
@@ -37,6 +37,7 @@ add_task(async function testBreakableLinesOverReloads() {
   await assertBreakableLines(dbg, "index.html", 21, [[15], [17]]);
 
   info("Assert breakable lines of the second orignal file");
+  await waitForSource(dbg, "original.js");
   // See first assertion about original.js,
   // the size of original.js doesn't match the size of the test file
   await assertBreakableLines(dbg, "original.js", 18, [[1,3], [8,11], [13]]);