Initial scroll-blocks-on compositor integration

LayoutTests/inspector/elements/styles/styles-new-API-expected.txt

 Tests that InspectorCSSAgent API methods work as expected.
 
 H1
 
 
 Running: test_styles
 
 === Computed style property count for body ===
 OK
 
@@ skipping 56 matching lines @@
 body::after: [regular, 26:0-26:11] {
     ['content':'"After body"'] @[27:4-27:26] 
 }
 
 === Inherited styles for body ===
 Level=1
 [NO STYLE]
 html: [user-agent] {
     ['display':'block'] @[undefined-undefined] 
 }
+:root: [user-agent] {
+    ['scroll-blocks-on':'start-touch wheel-event'] @[undefined-undefined] 
+}
 html: [regular, 4:0-4:4] {
     ['font-weight':'400'] @[5:4-5:21] 
 }
 
 === Inline style for body ===
 ['font-weight':'normal'] @[0:0-0:20] 
 ['width':'85%'] @[0:21-0:32] 
 ['background-image':'url(bar.png)'] @[0:33-0:63] 
 
 Running: test_forcedState
@@ skipping 313 matching lines @@
 ['border-top-color':'initial'] @[undefined-undefined] 
 ['border-right-color':'initial'] @[undefined-undefined] 
 ['border-bottom-color':'initial'] @[undefined-undefined] 
 ['border-left-color':'initial'] @[undefined-undefined] 
 ['border-image-source':'initial'] @[undefined-undefined] 
 ['border-image-slice':'initial'] @[undefined-undefined] 
 ['border-image-width':'initial'] @[undefined-undefined] 
 ['border-image-outset':'initial'] @[undefined-undefined] 
 ['border-image-repeat':'initial'] @[undefined-undefined]