Update a few references to imported/wpt (now external/wpt)

docs/testing/writing_layout_tests.md

Index: docs/testing/writing_layout_tests.md
diff --git a/docs/testing/writing_layout_tests.md b/docs/testing/writing_layout_tests.md
index 6399a7bbe79f94f801a9bec51a2c055c396b619a..0036a7acbc009b110d929d5426f5ed12996f68d7 100644
--- a/docs/testing/writing_layout_tests.md
+++ b/docs/testing/writing_layout_tests.md
@@ -190,7 +190,7 @@ and
 [/resources/testharnessreport.js](../../third_party/WebKit/LayoutTests/resources/testharnessreport.js).
 This is contrary to the WPT guidelines, which call for absolute paths.
 This limitation does not apply to the tests in `LayoutTests/http`, which rely on
-an HTTP server, or to the tests in `LayoutTests/imported/wpt`, which are
+an HTTP server, or to the tests in `LayoutTests/external/wpt`, which are
 imported from the [WPT repository](https://github.com/w3c/web-platform-tests).
 ***
 
@@ -471,7 +471,7 @@ body {
 ```
 
 *** promo
-Tests outside `LayoutTests/http` and `LayoutTests/imported/wpt` currently need
+Tests outside `LayoutTests/http` and `LayoutTests/external/wpt` currently need
 to use a relative path to
 [/third_party/WebKit/LayoutTests/resources/ahem.js](../../third_party/WebKit/LayoutTests/resources/ahem.js)
 ***