JavaScript: Fix two performance regressions in rc/1.20

javascript/ql/src/semmle/javascript/dataflow/Configuration.qll

@@ -570,10 +570,24 @@ private predicate reachableFromInput(
   callInputStep(f, invk, input, nd, cfg) and
   summary = PathSummary::level()
   or
-  exists(DataFlow::Node mid, PathSummary oldSummary, PathSummary newSummary |
+  exists(DataFlow::Node mid, PathSummary oldSummary |
     reachableFromInput(f, invk, input, mid, cfg, oldSummary) and
-    flowStep(mid, cfg, nd, newSummary) and
-    summary = oldSummary.append(newSummary)
+    appendStep(mid, cfg, oldSummary, nd, summary)
+  )
+}
+
+/**
+ * Holds if there is a step from `pred` to `succ` under `cfg` that can be appended
+ * to a path represented by `oldSummary` yielding a path represented by `newSummary`.
+ */
+pragma[noinline]
+private predicate appendStep(
+  DataFlow::Node pred, DataFlow::Configuration cfg, PathSummary oldSummary, DataFlow::Node succ,
+  PathSummary newSummary
+) {
+  exists(PathSummary stepSummary |
+    flowStep(pred, cfg, succ, stepSummary) and
+    newSummary = oldSummary.append(stepSummary)
   )
 }
 

javascript/ql/src/semmle/javascript/frameworks/Electron.qll

@@ -16,7 +16,7 @@ module Electron {
   /**
    * An instantiation of `BrowserWindow` or `BrowserView`.
    */
-  abstract private class NewBrowserObject extends BrowserObject, DataFlow::TrackedNode {
+  abstract private class NewBrowserObject extends BrowserObject, DataFlow::SourceNode {
     DataFlow::NewNode self;
 
     NewBrowserObject() { this = self }
@@ -250,10 +250,10 @@ module Electron {
     /**
      * An additional flow step  via an Electron IPC message.
      */
-    private class IPCAdditionalFlowStep extends DataFlow::Configuration {
-      IPCAdditionalFlowStep() { this instanceof DataFlow::Configuration }
+    private class IPCAdditionalFlowStep extends DataFlow::AdditionalFlowStep {
+      IPCAdditionalFlowStep() { ipcFlowStep(this, _) }
 
-      override predicate isAdditionalFlowStep(DataFlow::Node pred, DataFlow::Node succ) {
+      override predicate step(DataFlow::Node pred, DataFlow::Node succ) {
         ipcFlowStep(pred, succ)
       }
     }

javascript/ql/test/library-tests/frameworks/Electron/BrowserObject.expected

@@ -4,11 +4,7 @@
 | electron.js:3:10:3:48 | new Bro ... s: {}}) |
 | electron.js:4:5:4:46 | bv |
 | electron.js:4:10:4:46 | new Bro ... s: {}}) |
-| electron.js:35:14:35:14 | x |
-| electron.js:36:12:36:12 | x |
-| electron.js:39:1:39:7 | foo(bw) |
 | electron.js:39:5:39:6 | bw |
-| electron.js:40:1:40:7 | foo(bv) |
 | electron.js:40:5:40:6 | bv |
 | electron.ts:3:12:3:13 | bw |
 | electron.ts:3:40:3:41 | bv |

javascript/ql/test/library-tests/frameworks/Electron/IpcFlow.ql

@@ -1,9 +1,5 @@
 import javascript
 
-class TestConfig extends DataFlow::Configuration {
-  TestConfig() { this = "TestConfig" }
-}
-
-from TestConfig cfg, DataFlow::Node pred, DataFlow::Node succ
-where cfg.isAdditionalFlowStep(pred, succ)
+from DataFlow::AdditionalFlowStep afs, DataFlow::Node pred, DataFlow::Node succ
+where afs.step(pred, succ)
 select pred, succ

javascript/ql/test/library-tests/frameworks/Electron/WebContents.expected

@@ -1,4 +1,2 @@
-| electron.js:39:1:39:19 | foo(bw).webContents |
-| electron.js:40:1:40:19 | foo(bv).webContents |
 | electron.ts:4:3:4:16 | bw.webContents |
 | electron.ts:5:3:5:16 | bv.webContents |