[strong] Disallow implicit conversions for comparison

src/runtime.js

Index: src/runtime.js
diff --git a/src/runtime.js b/src/runtime.js
index 004f9bf61bcdd1a088f12696b7216c0ead17f1c6..fbe50c95a461f4f86f139074793a2dab9e23948d 100644
--- a/src/runtime.js
+++ b/src/runtime.js
@@ -19,6 +19,7 @@
 var EQUALS;
 var STRICT_EQUALS;
 var COMPARE;
+var COMPARE_STRONG;
 var ADD;
 var ADD_STRONG;
 var STRING_ADD_LEFT;
@@ -203,6 +204,14 @@ COMPARE = function COMPARE(x, ncr) {
   }
 }
 
+// Strong mode COMPARE throws if an implicit conversion would be performed
+COMPARE_STRONG = function COMPARE_STRONG(x, ncr) {
+  if (IS_STRING(this) && IS_STRING(x)) return %_StringCompare(this, x);
+  if (IS_NUMBER(this) && IS_NUMBER(x)) return %NumberCompare(this, x, ncr);
+
+  throw %MakeTypeError('strong_implicit_cast');
+}
+
 
 
 /* -----------------------------------