[DevTools] simplify script with source map blackboxing

Current logic produces one Debugger.setBlackboxedRanges call on each
scriptParsed event. It makes our frontend too much chatty.
This CL simplify blackbox manager. With new logic blackbox manager
sends Debugger.setBlackboxedRanges iff script has sourceMap and at
least one sourceURL from sourceMap is blackboxed.
When blackbox pattern changed frontend will send setBlackboxedRanges
iff ranges are affected by change.

R=lushnikov@chromium.org

Change-Id: I8b9511f9feba50127de4add98c8d191877103145
Reviewed-on: https://chromium-review.googlesource.com/1162308
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Andrey Lushnikov <lushnikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580742}

third_party/blink/renderer/devtools/front_end/bindings/CompilerScriptMapping.js

@@ -244,16 +244,6 @@ Bindings.CompilerScriptMapping = class {
     return this._sourceMapManager.sourceMapForClient(script);
   }
 
-  /**
-   * @param {!SDK.Script} script
-   */
-  maybeLoadSourceMap(script) {
-    const sourceMap = this._sourceMapManager.sourceMapForClient(script);
-    if (!sourceMap)
-      return;
-    this._populateSourceMapSources(script, sourceMap);
-  }
-
   /**
    * @param {?SDK.SourceMap} sourceMap
    */

third_party/blink/renderer/devtools/front_end/sdk/Script.js

@@ -254,10 +254,7 @@ SDK.Script = class {
   async setBlackboxedRanges(positions) {
     const response = await this.debuggerModel.target().debuggerAgent().invoke_setBlackboxedRanges(
         {scriptId: this.scriptId, positions});
-    const error = response[Protocol.Error];
-    if (error)
-      console.error(error);
-    return !error;
+    return !response[Protocol.Error];
   }
 };