[Devtools] Lazily build reverse mappings

third_party/WebKit/Source/devtools/front_end/bindings/BlackboxManager.js

Index: third_party/WebKit/Source/devtools/front_end/bindings/BlackboxManager.js
diff --git a/third_party/WebKit/Source/devtools/front_end/bindings/BlackboxManager.js b/third_party/WebKit/Source/devtools/front_end/bindings/BlackboxManager.js
index 5f20ec60fd80ac254bd3bb9442d2d8dc2e2580b7..5ba470cb223a1f052551c36d53c823b0aaeae41e 100644
--- a/third_party/WebKit/Source/devtools/front_end/bindings/BlackboxManager.js
+++ b/third_party/WebKit/Source/devtools/front_end/bindings/BlackboxManager.js
@@ -151,6 +151,19 @@ WebInspector.BlackboxManager.prototype = {
         if (!previousScriptState)
             return Promise.resolve();
 
+        var hasBlackboxedMappings = false;

[lushnikov, 2016/09/28 16:48:12]

what's this code about?

[eostroukhov, 2016/09/28 23:26:33]

There is no reason to check individual mappings if no source URLs from the
source map are blackboxed.

I rewrote the code a bit to make the change smaller.

[lushnikov, 2016/09/29 16:29:52]

Nice, thanks

+        for (var scriptURL of sourceMap.sourceURLs()) {
+            if (this.isBlackboxedURL(scriptURL)) {
+                hasBlackboxedMappings = true;
+                break;
+            }
+        }
+        if (!hasBlackboxedMappings) {
+            if (previousScriptState.length > 0)
+                return this._setScriptState(script, []);
+            return Promise.resolve();
+        }
+
         var mappings = sourceMap.mappings().slice();
         mappings.sort(mappingComparator);