diff --git a/src/com/google/javascript/jscomp/DataFlowAnalysis.java b/src/com/google/javascript/jscomp/DataFlowAnalysis.java
index 4255d183d29..c04d25454d4 100644
--- a/src/com/google/javascript/jscomp/DataFlowAnalysis.java
+++ b/src/com/google/javascript/jscomp/DataFlowAnalysis.java
@@ -16,6 +16,7 @@
 
 package com.google.javascript.jscomp;
 
+import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 
@@ -593,33 +594,31 @@ public void visit(NodeTraversal t, Node n, Node parent) {
   }
 
   /**
-   * Alternate implementation of compute escaped that accepts the child scope and the current
-   * jsScope to help us access both the function and function body scopes.
+   * Alternate implementation of compute escaped for ES6.
+   *
+   * It should only be run when the jsScope is a function scope.
    *
    * The definition of escaped are
    *   1. Exported variables as they can be needed after the script terminates.
-   *   2. Names of named functions because in JavaScript, <i>function foo(){}</i> does not kill
-   *       <i>foo</i> in the dataflow.
+   *   2. Names of named functions because in JavaScript, function foo(){} does not kill
+   *       foo in the dataflow.
+   *
    *
-   * @param jsScopeChild If jsScope is a function scope, jsScopeChild is the scope for the body of
-   *     that function. If not, jsScopeChild is null.
    */
-  static void computeEscaped(
+  static void computeEscapedEs6(
       final Scope jsScope,
-      final Scope jsScopeChild,
       final Set<Var> escaped,
       AbstractCompiler compiler,
       Es6SyntacticScopeCreator scopeCreator) {
 
+    checkArgument(jsScope.isFunctionScope());
+
     AbstractPostOrderCallback finder =
         new AbstractPostOrderCallback() {
           @Override
           public void visit(NodeTraversal t, Node n, Node parent) {
 
-            Node enclosingBlock = NodeUtil.getEnclosingScopeRoot(n);
-            if (jsScope.isFunctionScope()) {
-              enclosingBlock = NodeUtil.getEnclosingFunction(n);
-            }
+            Node enclosingBlock = NodeUtil.getEnclosingFunction(n);
             if (jsScope.getRootNode() == enclosingBlock || !n.isName() || parent.isFunction()) {
               return;
             }
@@ -627,10 +626,8 @@ public void visit(NodeTraversal t, Node n, Node parent) {
             String name = n.getString();
             Var var = t.getScope().getVar(name);
             if (var != null) {
-              Node enclosingScopeNode = NodeUtil.getEnclosingScopeRoot(var.getNode());
-              if (jsScope.isFunctionScope()) {
-                enclosingScopeNode = NodeUtil.getEnclosingFunction(var.getNode());
-              }
+              Node enclosingScopeNode = NodeUtil.getEnclosingFunction(var.getNode());
+
               if (enclosingScopeNode == jsScope.getRootNode()) {
                 escaped.add(var);
               }
diff --git a/src/com/google/javascript/jscomp/LiveVariablesAnalysisEs6.java b/src/com/google/javascript/jscomp/LiveVariablesAnalysisEs6.java
index 1123202c769..bac35ae9d85 100644
--- a/src/com/google/javascript/jscomp/LiveVariablesAnalysisEs6.java
+++ b/src/com/google/javascript/jscomp/LiveVariablesAnalysisEs6.java
@@ -144,7 +144,7 @@ public int hashCode() {
     this.escaped = new HashSet<>();
     this.scopeVariables = new HashMap<>();
     this.allVarsInFn = new HashMap<>();
-    computeEscaped(jsScope, jsScopeChild, escaped, compiler, scopeCreator);
+    computeEscapedEs6(jsScope, escaped, compiler, scopeCreator);
     NodeUtil.getAllVarsDeclaredInFunction(allVarsInFn, compiler, scopeCreator, jsScope);
     addScopeVariables();
   }
@@ -329,7 +329,7 @@ private void addToSetIfLocal(Node node, BitSet set) {
     // to the function body.
     if (localScope.isFunctionBlockScope()) {
       local = localScope.isDeclaredInFunctionBlockOrParameter(name);
-    } else if (jsScopeChild != null && localScope == jsScope) {
+    } else if (localScope == jsScope) {
       local = jsScopeChild.isDeclaredInFunctionBlockOrParameter(name);
     } else {
       local = localScope.isDeclared(name, false);
@@ -350,27 +350,15 @@ private void addToSetIfLocal(Node node, BitSet set) {
    * escaped set.
    */
   void markAllParametersEscaped() {
-    if (jsScope.isFunctionScope()) {
-      Node paramList = NodeUtil.getFunctionParameters(jsScope.getRootNode());
-      for (Node arg = paramList.getFirstChild(); arg != null; arg = arg.getNext()) {
-        escaped.add(jsScope.getVar(arg.getString()));
-      }
-    } else {
-      Node enclosingFunction = NodeUtil.getEnclosingFunction(jsScope.getRootNode());
-      Node paramList = NodeUtil.getFunctionParameters(enclosingFunction);
-      for (Node arg = paramList.getFirstChild(); arg != null; arg = arg.getNext()) {
-        escaped.add(jsScope.getVar(arg.getString()));
-      }
+    Node paramList = NodeUtil.getFunctionParameters(jsScope.getRootNode());
+    for (Node arg = paramList.getFirstChild(); arg != null; arg = arg.getNext()) {
+      escaped.add(jsScope.getVar(arg.getString()));
     }
   }
 
   private boolean isArgumentsName(Node n) {
     boolean childDeclared;
-    if (jsScopeChild != null) {
-      childDeclared = jsScopeChild.isDeclared(ARGUMENT_ARRAY_ALIAS, false);
-    } else {
-      childDeclared = true;
-    }
+    childDeclared = jsScopeChild.isDeclared(ARGUMENT_ARRAY_ALIAS, false);
     return n.isName()
         && n.getString().equals(ARGUMENT_ARRAY_ALIAS)
         && (!jsScope.isDeclared(ARGUMENT_ARRAY_ALIAS, false) || !childDeclared);
diff --git a/src/com/google/javascript/jscomp/MaybeReachingVariableUse.java b/src/com/google/javascript/jscomp/MaybeReachingVariableUse.java
index db39a943666..950fb12601a 100644
--- a/src/com/google/javascript/jscomp/MaybeReachingVariableUse.java
+++ b/src/com/google/javascript/jscomp/MaybeReachingVariableUse.java
@@ -61,7 +61,7 @@ class MaybeReachingVariableUse extends
 
     // TODO(user): Maybe compute it somewhere else and re-use the escape
     // local set here.
-    computeEscaped(jsScope.getParent(), jsScope, escaped, compiler, scopeCreator);
+    computeEscapedEs6(jsScope.getParent(), escaped, compiler, scopeCreator);
     NodeUtil.getAllVarsDeclaredInFunction(allVarsInFn, compiler, scopeCreator, jsScope.getParent());
   }
 
diff --git a/src/com/google/javascript/jscomp/MustBeReachingVariableDef.java b/src/com/google/javascript/jscomp/MustBeReachingVariableDef.java
index 79f8ab50499..eee7168b66f 100644
--- a/src/com/google/javascript/jscomp/MustBeReachingVariableDef.java
+++ b/src/com/google/javascript/jscomp/MustBeReachingVariableDef.java
@@ -56,7 +56,7 @@ final class MustBeReachingVariableDef extends
     this.compiler = compiler;
     this.escaped = new HashSet<>();
     this.allVarsInFn = new HashMap<>();
-    computeEscaped(jsScope.getParent(), jsScope, escaped, compiler, scopeCreator);
+    computeEscapedEs6(jsScope.getParent(), escaped, compiler, scopeCreator);
     NodeUtil.getAllVarsDeclaredInFunction(
         allVarsInFn, compiler, scopeCreator, jsScope.getParent());
   }