[[FIX]] Do not duplicate reported warnings/errors

Extend the testing infrastructure to recognize cases where identical
warnings/errors are being reported, and address the areas of the code
base that previously suffered from this problem.

src/jshint.js

@@ -1347,13 +1347,7 @@ var JSHINT = (function() {
       state.nameStack.set(state.tokens.prev);
       return true;
     } else if (left.id === "{" || left.id === "[") {
-      if (allowDestructuring && left.destructAssign) {
-        left.destructAssign.forEach(function(t) {
-          if (t.id) {
-            state.funct["(scope)"].block.modify(t.id, t.token);
-          }
-        });
-      } else {
+      if (!allowDestructuring || !left.destructAssign) {
         if (left.id === "{" || !left.left) {
           warning("E031", assignToken);
         } else if (left.left.value === "arguments" && !state.isStrict()) {
@@ -4410,10 +4404,9 @@ var JSHINT = (function() {
   stmt("continue", function() {
     var v = state.tokens.next.value;
 
-    if (state.funct["(breakage)"] === 0)
-      warning("W052", state.tokens.next, this.value);
-    if (!state.funct["(loopage)"])
+    if (state.funct["(breakage)"] === 0 || !state.funct["(loopage)"]) {
       warning("W052", state.tokens.next, this.value);
+    }
 
     if (!state.option.asi)
       nolinebreak(this);

tests/helpers/testhelper.js

@@ -111,6 +111,12 @@ exports.setup.testRun = function (test, name) {
       }).filter(function (er) {
         return !!er;
       });
+      var duplicateErrors = errors.filter(function (er) {
+        return errors.filter(function (other) {
+          return er.line === other.line && er.character === other.character &&
+            er.reason === other.reason;
+        }).length > 1;
+      });
 
       // remove undefined errors, if there is a definition with wrong line number
       undefinedErrors = undefinedErrors.filter(function (er) {
@@ -126,7 +132,8 @@ exports.setup.testRun = function (test, name) {
 
       test.ok(
         undefinedErrors.length === 0
-          && unthrownErrors.length === 0 && wrongLineNumbers.length === 0,
+          && unthrownErrors.length === 0 && wrongLineNumbers.length === 0
+          && duplicateErrors.length === 0,
 
         (name === null ? "" : "\n  TestRun: [bold]{" + name + "}") +
         unthrownErrors.map(function (el, idx) {
@@ -140,6 +147,10 @@ exports.setup.testRun = function (test, name) {
         wrongLineNumbers.map(function (el, idx) {
           return (idx === 0 ? "\n  [yellow]{Errors with wrong line number}\n" : "") +
             "  [bold]{Line " + el.line + "} " + el.message + " [red]{not in line(s)} [bold]{" + el.definedIn.join(", ") + "}";
+        }).join("\n") +
+        duplicateErrors.map(function (el, idx) {
+          return (idx === 0 ? "\n  [yellow]{Duplicated errors}\n": "") +
+            "  [bold]{Line " + el.line + ", Char " + el.character + "} " + el.reason;
         }).join("\n") + "\n"
       );
     }