JavaScript: Unify (most) overrides of getAnImportedModule.

javascript/ql/src/semmle/javascript/AMD.qll

@@ -222,8 +222,6 @@ class AMDModule extends Module {
   /** Gets the definition of this module. */
   AMDModuleDefinition getDefine() { amdModuleTopLevel(result, this) }
 
-  override Module getAnImportedModule() { result.getFile() = resolve(getDefine().getADependency()) }
-
   override predicate exports(string name, ASTNode export) {
     exists(DataFlow::PropWrite pwn | export = pwn.getAstNode() |
       pwn.getBase().analyze().getAValue() = getDefine().getAModuleExportsValue() and

javascript/ql/src/semmle/javascript/ES2015Modules.qll

@@ -19,8 +19,6 @@ class ES2015Module extends Module {
   /** Gets an export declaration in this module. */
   ExportDeclaration getAnExport() { result.getTopLevel() = this }
 
-  override Module getAnImportedModule() { result = getAnImport().getImportedModule() }
-
   override predicate exports(string name, ASTNode export) {
     exists(ExportDeclaration ed | ed = getAnExport() and ed = export | ed.exportsAs(_, name))
   }

javascript/ql/src/semmle/javascript/Modules.qll

@@ -21,7 +21,7 @@ abstract class Module extends TopLevel {
   Import getAnImport() { result.getTopLevel() = this }
 
   /** Gets a module from which this module imports. */
-  abstract Module getAnImportedModule();
+  Module getAnImportedModule() { result = getAnImport().getImportedModule() }
 
   /** Gets a symbol exported by this module. */
   string getAnExportedSymbol() { exports(result, _) }

javascript/ql/src/semmle/javascript/NodeJS.qll

@@ -21,9 +21,6 @@ class NodeModule extends Module {
   /** Gets the scope induced by this module. */
   override ModuleScope getScope() { result.getScopeElement() = this }
 
-  /** Gets a module imported by this module. */
-  override Module getAnImportedModule() { result = getAnImport().getImportedModule() }
-
   /**
    * Gets an abstract value representing one or more values that may flow
    * into this module's `module.exports` property.