DevTools: do not detach sourcemap in case of style sheet editing

third_party/WebKit/LayoutTests/inspector/elements/styles-4/styles-do-not-detach-sourcemap-on-edits-expected.txt

Index: third_party/WebKit/LayoutTests/inspector/elements/styles-4/styles-do-not-detach-sourcemap-on-edits-expected.txt
diff --git a/third_party/WebKit/LayoutTests/inspector/elements/styles-4/styles-do-not-detach-sourcemap-on-edits-expected.txt b/third_party/WebKit/LayoutTests/inspector/elements/styles-4/styles-do-not-detach-sourcemap-on-edits-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..c0e5b1ef714132b97dbfca1055ea7040359de681
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/inspector/elements/styles-4/styles-do-not-detach-sourcemap-on-edits-expected.txt
@@ -0,0 +1,82 @@
+Tests that source map is not detached on edits. crbug.com/257778
+
+container.
+
+Running: editProperty
+[expanded] 
+element.style { ()
+
+[expanded] 
+@media (min-width: 6px)
+#container { (styles-do-not-d…n-edits.scss:2 -> styles-do-not-detach-sourcemap-on-edits.scss:2:5)
+    border: 1px solid blue;
+    color: blue;
+
+[expanded] 
+div { (user agent stylesheet)
+    display: block;
+
+
+Running: editSelector
+[expanded] 
+element.style { ()
+
+[expanded] 
+@media (min-width: 6px)
+#container { (styles-do-not-d…n-edits.scss:2 -> styles-do-not-detach-sourcemap-on-edits.scss:2:5)
+    border: 1px solid blue;
+/-- overloaded --/     NAME: VALUE;
+
+[expanded] 
+div { (user agent stylesheet)
+    display: block;
+
+
+Running: editMedia
+[expanded] 
+element.style { ()
+
+[expanded] 
+@media (min-width: 6px)
+#container, SELECTOR { (styles-do-not-d…n-edits.scss:2 -> styles-do-not-detach-sourcemap-on-edits.scss:2:5)
+    border: 1px solid blue;
+/-- overloaded --/     NAME: VALUE;
+
+[expanded] 
+div { (user agent stylesheet)
+    display: block;
+
+
+Running: addRule
+[expanded] 
+element.style { ()
+
+[expanded] 
+@media (max-width: 9999999px)
+#container, SELECTOR { (styles-do-not-d…n-edits.scss:2 -> styles-do-not-detach-sourcemap-on-edits.scss:2:5)
+    border: 1px solid blue;
+/-- overloaded --/     NAME: VALUE;
+
+[expanded] 
+div { (user agent stylesheet)
+    display: block;
+
+
+Running: finish
+[expanded] 
+element.style { ()
+
+[expanded] [no-affect] 
+NEW-RULE { (styles-do-not-d…n-edits.scss:4 -> styles-do-not-detach-sourcemap-on-edits.scss:4:20)
+
+[expanded] 
+@media (max-width: 9999999px)
+#container, SELECTOR { (styles-do-not-d…n-edits.scss:2 -> styles-do-not-detach-sourcemap-on-edits.scss:2:5)
+    border: 1px solid blue;
+/-- overloaded --/     NAME: VALUE;
+
+[expanded] 
+div { (user agent stylesheet)
+    display: block;
+
+