Bug 1278823 - styleeditor: fix csscoverage report creation;r=jryans

The sheetToUrl function in csscoverage is only used to create ids for the
csscoverage map of knownRules. Instead of asking the UI to format stylesheet
URLs using the same logic as the server, StyleEditor.jsm now sends the
stylesheet actor to create the report. The csscoverage actor can then compute
the stylesheet URL on the server.

MozReview-Commit-ID: GDtWhbi2ScW

devtools/shared/specs/csscoverage.js

@@ -5,6 +5,8 @@
 
 const {Arg, RetVal, generateActorSpec} = require("devtools/shared/protocol");
 
+require("devtools/shared/specs/stylesheets");
+
 const cssUsageSpec = generateActorSpec({
   typeName: "cssUsage",
 
@@ -26,6 +28,10 @@ const cssUsageSpec = generateActorSpec({
       request: { url: Arg(0, "string") },
       response: { reports: RetVal("array:json") }
     },
+    createEditorReportForSheet: {
+      request: { url: Arg(0, "stylesheet") },
+      response: { reports: RetVal("array:json") }
+    },
     createPageReport: {
       response: RetVal("json")
     },