[strong] Disallow implicit conversions for binary arithmetic operations

src/messages.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // -------------------------------------------------------------------
 
 var kMessages = {
   // Error
   constructor_is_generator:      ["Class constructor may not be a generator"],
   constructor_is_accessor:       ["Class constructor may not be an accessor"],
@@ skipping 114 matching lines @@
   strict_delete_property:        ["Cannot delete property '", "%0", "' of ", "%1"],
   strict_function:               ["In strict mode code, functions can only be declared at top level or immediately within another function." ],
   strict_read_only_property:     ["Cannot assign to read only property '", "%0", "' of ", "%1"],
   strict_cannot_assign:          ["Cannot assign to read only '", "%0", "' in strict mode"],
   restricted_function_properties: ["'caller' and 'arguments' are restricted function properties and cannot be accessed in this context."],
   strict_poison_pill:            ["'caller', 'callee', and 'arguments' properties may not be accessed on strict mode functions or the arguments objects for calls to them"],
   strict_caller:                 ["Illegal access to a strict mode caller function."],
   strong_ellision:               ["In strong mode, arrays with holes are deprecated, use maps instead"],
   strong_arguments:              ["In strong mode, 'arguments' is deprecated, use '...args' instead"],
   strong_undefined:              ["In strong mode, binding or assigning to 'undefined' is deprecated"],
+  strong_implicit_cast:          ["In strong mode, implicit casts are deprecated"],

[rossberg, 2015/04/23 13:29:37]

Nit: "casts" -> "conversions"

   strong_direct_eval:            ["In strong mode, direct calls to eval are deprecated"],
   strong_switch_fallthrough :    ["In strong mode, switch fall-through is deprecated, terminate each case with 'break', 'continue', 'return' or 'throw'"],
   strong_equal:                  ["In strong mode, '==' and '!=' are deprecated, use '===' and '!==' instead"],
   strong_delete:                 ["In strong mode, 'delete' is deprecated, use maps or sets instead"],
   strong_var:                    ["In strong mode, 'var' is deprecated, use 'let' or 'const' instead"],
   strong_for_in:                 ["In strong mode, 'for'-'in' loops are deprecated, use 'for'-'of' instead"],
   strong_empty:                  ["In strong mode, empty sub-statements are deprecated, make them explicit with '{}' instead"],
   strong_use_before_declaration: ["In strong mode, declaring variable '", "%0", "' before its use is required"],
   strong_unbound_global:         ["In strong mode, using an undeclared global variable '", "%0", "' is not allowed"],
   strong_super_call_missing:     ["In strong mode, invoking the super constructor in a subclass is required"],
@@ skipping 1120 matching lines @@
 function SetUpStackOverflowBoilerplate() {
   var boilerplate = MakeRangeError(kStackOverflow);
 
   %DefineAccessorPropertyUnchecked(
       boilerplate, 'stack', StackTraceGetter, StackTraceSetter, DONT_ENUM);
 
   return boilerplate;
 }
 
 var kStackOverflowBoilerplate = SetUpStackOverflowBoilerplate();