fix infinite loop in acorn_loose when parsing broken import

node_modules/treehugger/lib/acorn/dist/acorn_loose.js

@@ -1146,6 +1146,7 @@ lp.parseImportSpecifierList = function () {
     this.pushCx();
     this.eat(tt.braceL);
     if (this.curLineStart > continuedLine) continuedLine = this.curLineStart;
+    var lastTokenStart = -1;
     while (!this.closes(tt.braceR, indent + (this.curLineStart <= continuedLine ? 1 : 0), line)) {
       var elt = this.startNode();
       if (this.eat(tt.star)) {
@@ -1157,6 +1158,8 @@ lp.parseImportSpecifierList = function () {
         elt.local = this.eatContextual("as") ? this.parseIdent() : elt.imported;
         this.finishNode(elt, "ImportSpecifier");
       }
+      if (elt.start == lastTokenStart) break;
+      lastTokenStart = elt.start;
       elts.push(elt);
       this.eat(tt.comma);
     }