Rename AstFactory.declareSingleLet() to match other methods

Methods in AstFactory are named createThing() except for declareSingleLet(),
so I'm fixing that inconsistency.

I'm also dropping the JSType argument, because applying a type other than VOID_TYPE
is inconsistent with the type that TypeInference would apply to the declaration.

PiperOrigin-RevId: 321803894

Author: brad4d

src/com/google/javascript/jscomp/AstFactory.java

@@ -362,12 +362,12 @@ Node createThisAliasDeclarationForFunction(String aliasName, Node functionNode)
   }
 
   /**
-   * Creates a new `let` declaration with a type but no value.
+   * Creates a new `let` declaration for a single variable name with a void type and no JSDoc.
    *
    * <p>e.g. `let variableName`
    */
-  Node declareSingleLet(String variableName, JSType type) {
-    return IR.let(createName(variableName, type));
+  Node createSingleLetNameDeclaration(String variableName) {
+    return IR.let(createName(variableName, JSTypeNative.VOID_TYPE));
   }
 
   /**

src/com/google/javascript/jscomp/RewriteNullishCoalesceOperator.java

@@ -75,7 +75,7 @@ private void visitNullishCoalesce(NodeTraversal t, Node n) {
     Node left = n.removeFirstChild();
     Node right = n.getLastChild().detach();
 
-    Node let = astFactory.declareSingleLet(tempVarName, left.getJSType());
+    Node let = astFactory.createSingleLetNameDeclaration(tempVarName);
     Node assignName = astFactory.createName(tempVarName, left.getJSType());
     Node assign = astFactory.createAssign(assignName, left);
     Node ne = astFactory.createNe(assign, astFactory.createNull());