script: Eliminate code duplication in the task queue (#34798)

Instead of creating a type for each `TaskSource` variety have each `TaskSource`
hold the same kind of sender (this was inconsistent before, but each
sender was effectively the same trait object), a pipeline, and a
`TaskSourceName`. This elminates the need to reimplement the same
queuing code for every task source.

In addition, have workers hold their own `TaskManager`. This allows just
exposing the manager on the `GlobalScope`. Currently the `TaskCanceller`
is different, but this will also be eliminated in a followup change.

This is a the first step toward having a shared set of `Sender`s on
`GlobalScope`.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

components/shared/background_hang_monitor/lib.rs

@@ -27,6 +27,7 @@ pub enum ScriptHangAnnotation {
     InputEvent,
     HistoryEvent,
     NetworkEvent,
+    Rendering,
     Resize,
     ScriptEvent,
     SetScrollState,

components/shared/profile/time.rs

@@ -100,20 +100,21 @@ pub enum ProfilerCategory {
 
     ScriptPlannedNavigation = 0x6c,
     ScriptResize = 0x6d,
-    ScriptSetScrollState = 0x6e,
-    ScriptSetViewport = 0x6f,
-    ScriptTimerEvent = 0x70,
-    ScriptStylesheetLoad = 0x71,
-    ScriptUpdateReplacedElement = 0x72,
-    ScriptWebSocketEvent = 0x73,
-    ScriptWorkerEvent = 0x74,
-    ScriptServiceWorkerEvent = 0x75,
+    ScriptRendering = 0x6e,
+    ScriptSetScrollState = 0x6f,
+    ScriptSetViewport = 0x70,
+    ScriptTimerEvent = 0x71,
+    ScriptStylesheetLoad = 0x72,
+    ScriptUpdateReplacedElement = 0x73,
+    ScriptWebSocketEvent = 0x74,
+    ScriptWorkerEvent = 0x75,
+    ScriptServiceWorkerEvent = 0x76,
 
     /// The script thread is parsing XML, rather than doing other work like evaluating scripts or doing layout.
-    ScriptParseXML = 0x76,
+    ScriptParseXML = 0x77,
 
-    ScriptEnterFullscreen = 0x77,
-    ScriptExitFullscreen = 0x78,
+    ScriptEnterFullscreen = 0x78,
+    ScriptExitFullscreen = 0x79,
     ScriptWorkletEvent = 0x7a,
     ScriptPerformanceEvent = 0x7b,
     ScriptHistoryEvent = 0x7c,
@@ -157,6 +158,7 @@ impl ProfilerCategory {
             ProfilerCategory::ScriptNetworkEvent => "ScriptNetworkEvent",
             ProfilerCategory::ScriptParseHTML => "ScriptParseHTML",
             ProfilerCategory::ScriptPlannedNavigation => "ScriptPlannedNavigation",
+            ProfilerCategory::ScriptRendering => "ScriptRendering",
             ProfilerCategory::ScriptResize => "ScriptResize",
             ProfilerCategory::ScriptSetScrollState => "ScriptSetScrollState",
             ProfilerCategory::ScriptSetViewport => "ScriptSetViewport",