[[FIX]] Remove warning W100

No justification could be found for this warning. See
#2741

src/lex.js

@@ -1516,13 +1516,6 @@ Lexer.prototype = {
       this.input.search(/(\u00A0)/) : -1;
   },
 
-  /*
-   * Scan for characters that get silently deleted by one or more browsers.
-   */
-  scanUnsafeChars: function() {
-    return this.input.search(reg.unsafeChars);
-  },
-
   /*
    * Produce the next raw token or return 'null' if no tokens can be matched.
    * This method skips over all space characters.
@@ -1615,16 +1608,6 @@ Lexer.prototype = {
     }
 
     this.input = this.input.replace(/\t/g, state.tab);
-    char = this.scanUnsafeChars();
-
-    if (char >= 0) {
-      this.triggerAsync(
-        "warning",
-        { code: "W100", line: this.line, character: char },
-        checks,
-        function() { return true; }
-      );
-    }
 
     // If there is a limit on line length, warn when lines get too
     // long.

src/messages.js

@@ -188,7 +188,7 @@ var warnings = {
   W097: "Use the function form of \"use strict\".",
   W098: "'{a}' is defined but never used.",
   W099: null,
-  W100: "This character may get silently deleted by one or more browsers.",
+  W100: null,
   W101: "Line is too long.",
   W102: null,
   W103: "The '{a}' property is deprecated.",

src/reg.js

@@ -10,10 +10,6 @@
 exports.unsafeString =
   /@cc|<\/?|script|\]\s*\]|<\s*!|&lt/i;
 
-// Unsafe characters that are silently deleted by one or more browsers (cx)
-exports.unsafeChars =
-  /[\u0000-\u001f\u007f-\u009f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/;
-
 // Characters in strings that need escaping (nx and nxg)
 exports.needEsc =
   /[\u0000-\u001f&<"\/\\\u007f-\u009f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/;

tests/unit/parser.js

@@ -9,13 +9,16 @@ var fs    = require('fs');
 var TestRun = require("../helpers/testhelper").setup.testRun;
 var path    = require("path");
 
+/**
+ * The warning for this input was intentionally disabled after research into
+ * its justification produced no results.
+ */
 exports.unsafe = function (test) {
   var code = [
     "var a\u000a = 'Here is a unsafe character';",
   ];
 
   TestRun(test)
-    .addError(1, 5, "This character may get silently deleted by one or more browsers.")
     .test(code, {es3: true});
 
   test.done();
@@ -26,36 +29,30 @@ exports.peekOverDirectives = function (test) {
 
   TestRun(test)
     // Within object literal
-    .addError(18, 15, "This character may get silently deleted by one or more browsers.")
     .addError(18, 14, "Unexpected control character in regular expression.")
     .addError(19, 14, "Unexpected escaped character '<' in regular expression.")
     .addError(20, 81, "Line is too long.")
     .addError(21, 15, "Control character in string: <non-printable>.")
-    .addError(21, 14, "This character may get silently deleted by one or more browsers.")
     .addError(22, 14, "'Octal integer literal' is only available in ES6 (use 'esversion: 6').")
     .addError(23, 14, "'Binary integer literal' is only available in ES6 (use 'esversion: 6').")
     .addError(24, 14, "'template literal syntax' is only available in ES6 (use 'esversion: 6').")
     .addError(25, 14, "'Sticky RegExp flag' is only available in ES6 (use 'esversion: 6').")
 
     // Within array literal:
-    .addError(44, 4, "This character may get silently deleted by one or more browsers.")
     .addError(44, 3, "Unexpected control character in regular expression.")
     .addError(45, 3, "Unexpected escaped character '<' in regular expression.")
     .addError(46, 81, "Line is too long.")
     .addError(47, 4, "Control character in string: <non-printable>.")
-    .addError(47, 3, "This character may get silently deleted by one or more browsers.")
     .addError(48, 3, "'Octal integer literal' is only available in ES6 (use 'esversion: 6').")
     .addError(49, 3, "'Binary integer literal' is only available in ES6 (use 'esversion: 6').")
     .addError(50, 3, "'template literal syntax' is only available in ES6 (use 'esversion: 6').")
     .addError(51, 3, "'Sticky RegExp flag' is only available in ES6 (use 'esversion: 6').")
 
     // Within grouping operator:
-    .addError(70, 4, "This character may get silently deleted by one or more browsers.")
     .addError(70, 3, "Unexpected control character in regular expression.")
     .addError(71, 3, "Unexpected escaped character '<' in regular expression.")
     .addError(72, 81, "Line is too long.")
     .addError(73, 4, "Control character in string: <non-printable>.")
-    .addError(73, 3, "This character may get silently deleted by one or more browsers.")
     .addError(74, 3, "'Octal integer literal' is only available in ES6 (use 'esversion: 6').")
     .addError(75, 3, "'Binary integer literal' is only available in ES6 (use 'esversion: 6').")
     .addError(76, 3, "'template literal syntax' is only available in ES6 (use 'esversion: 6').")
@@ -574,9 +571,7 @@ exports.regexp = function (test) {
   ];
 
   var run = TestRun(test)
-    .addError(1, 11, "This character may get silently deleted by one or more browsers.")
     .addError(1, 10, "Unexpected control character in regular expression.")
-    .addError(2, 12, "This character may get silently deleted by one or more browsers.")
     .addError(2, 10, "Unexpected control character in regular expression.")
     .addError(3, 10, "Unexpected escaped character '<' in regular expression.")
     .addError(4, 10, "Unexpected escaped character '<' in regular expression.")
@@ -723,7 +718,6 @@ exports.strings = function (test) {
 
   var run = TestRun(test)
     .addError(1, 10, "Control character in string: <non-printable>.")
-    .addError(1, 9, "This character may get silently deleted by one or more browsers.")
     .addError(7, 12, "Unclosed string.")
     .addError(7, 12, "Missing semicolon.");
   run.test(code, {es3: true});