DevTools: defer styles delta calculation to until the end of the task.

LayoutTests/inspector/elements/styles/dynamic-style-tag-expected.txt

Index: LayoutTests/inspector/elements/styles/dynamic-style-tag-expected.txt
diff --git a/LayoutTests/inspector/elements/styles/dynamic-style-tag-expected.txt b/LayoutTests/inspector/elements/styles/dynamic-style-tag-expected.txt
index aa466d7f90e935c0ac49c385fc8334bc500afce3..828ac5340ef8ce7623a96b9c314560c26cf02664 100644
--- a/LayoutTests/inspector/elements/styles/dynamic-style-tag-expected.txt
+++ b/LayoutTests/inspector/elements/styles/dynamic-style-tag-expected.txt
@@ -1,33 +1,22 @@
 Tests that different types of inline styles are correctly disambiguated and their sourceURL is correct.
 
+Page reloaded.
 Stylesheet added:
-  - isInline: true
-  - sourceURL: dynamic-style-tag.html
+  - isInline: false
+  - sourceURL: 
   - hasSourceURL: false
   - contents: 
-/* comment */.inline-style-added-by-parser {
-   color: red;
-}
-
-Stylesheet added:
-  - isInline: true
-  - sourceURL: inlineStyleAddedByParser.css
-  - hasSourceURL: true
-  - contents: 
-.inline-style-added-by-parser-with-source-url {
-   color: green;
+.inline-style-added-by-parser-in-document-write {
+   color: blue;
 }
-/*# sourceURL=inlineStyleAddedByParser.css*/
 
 Stylesheet added:
   - isInline: false
   - sourceURL: 
   - hasSourceURL: false
-  - contents: 
-.inline-style-added-by-parser-in-document-write {
-   color: blue;
+  - contents: .inline-style-created-by-script {
+   color: orange;
 }
-
 Stylesheet added:
   - isInline: false
   - sourceURL: inlineStyleAddedByDocumentWrite.css
@@ -40,20 +29,31 @@ Stylesheet added:
 
 Stylesheet added:
   - isInline: false
-  - sourceURL: 
-  - hasSourceURL: false
-  - contents: .inline-style-created-by-script {
-   color: orange;
-}
-Stylesheet added:
-  - isInline: false
   - sourceURL: inlineStyleCreatedByScript.css
   - hasSourceURL: true
   - contents: .inline-style-created-by-script-with-source-url {
    color: grey;
 }
 /*# sourceURL=inlineStyleCreatedByScript.css*/
-Page reloaded.
+Stylesheet added:
+  - isInline: true
+  - sourceURL: dynamic-style-tag.html
+  - hasSourceURL: false
+  - contents: 
+/* comment */.inline-style-added-by-parser {
+   color: red;
+}
+
+Stylesheet added:
+  - isInline: true
+  - sourceURL: inlineStyleAddedByParser.css
+  - hasSourceURL: true
+  - contents: 
+.inline-style-added-by-parser-with-source-url {
+   color: green;
+}
+/*# sourceURL=inlineStyleAddedByParser.css*/
+
 [expanded] 
 element.style  { ()
 color: red;