message: Include source specifier in Analyzer Export feature.
diff: @@ -45,11 +45,13 @@ export class Export implements Resolvable, Feature {
  readonly astNode: JsAstNode<ExportNode>;
  readonly statementAst: babel.Statement;
  readonly warnings: ReadonlyArray<Warning> = [];
  + /** The original source module specifier from the `from` clause. */
  + readonly sourceSpecifier?: string;
  constructor(
  astNode: JsAstNode<ExportNode>, statementAst: babel.Statement,
  sourceRange: SourceRange|undefined, nodePath: NodePath<babel.Node>,
  - exportingAllFrom?: Iterable<Export>) {
  + exportingAllFrom?: Iterable<Export>, sourceSpecifier?: string) {
  this.astNode = astNode;
  this.statementAst = statementAst;
  let exportedIdentifiers;
  @@ -66,6 +68,7 @@ export class Export implements Resolvable, Feature {
  this.astNodePath = nodePath;
  this.sourceRange = sourceRange;
  + this.sourceSpecifier = sourceSpecifier;
  }
  // TODO: Could potentially get a speed boost by doing the Reference
  @@ -85,7 +88,8 @@ export class Export implements Resolvable, Feature {
  this.statementAst,
  this.sourceRange,
  this.astNodePath,
  - import_.document.getFeatures({kind: 'export'}));
  + import_.document.getFeatures({kind: 'export'}),
  + this.sourceSpecifier);
  }
  // It's immutable, and it doesn't care about other documents, so it's
  // both a ScannedFeature and a Feature. This is just one step in an
  @@ -116,14 +120,18 @@ export class JavaScriptExportScanner implements JavaScriptScanner {
  {language: 'js', containingDocument: document, node},
  esutil.getCanonicalStatement(path)!,
  document.sourceRangeForNode(node),
  - path));
  + path,
  + undefined,
  + node.source && node.source.value));
  },
  enterExportAllDeclaration(node, _parent, path) {
  exports.push(new Export(
  {language: 'js', containingDocument: document, node},
  esutil.getCanonicalStatement(path)!,
  document.sourceRangeForNode(node),
  - path));
  + path,
  + undefined,
  + node.source && node.source.value));
  },
  enterExportDefaultDeclaration(node, _parent, path) {
  exports.push(new Export(
  