Normative: eval(nonString) should not have observable side effects (#…

…1504)

Fixes #1495
which identifies the ordering of host callouts and input type checks as a spec bug.

This uses option 1 from #1495 (comment)
to ensure that type checks happen before host callouts.

This can't be tested in test262 but if this lands, I will follow up with tests via web-platform-tests/wpt.

spec.html

@@ -12569,13 +12569,12 @@ <h1>Runtime Semantics: Evaluation</h1>
               1. Let _evalText_ be the first element of _argList_.
               1. If the source code matching this |CallExpression| is strict mode code, let _strictCaller_ be *true*. Otherwise let _strictCaller_ be *false*.
               1. Let _evalRealm_ be the current Realm Record.
-              1. Perform ? HostEnsureCanCompileStrings(_evalRealm_, _evalRealm_).
               1. Return ? PerformEval(_evalText_, _evalRealm_, _strictCaller_, *true*).
           1. Let _thisCall_ be this |CallExpression|.
           1. Let _tailCall_ be IsInTailPosition(_thisCall_).
           1. Return ? EvaluateCall(_func_, _ref_, _arguments_, _tailCall_).
         </emu-alg>
-        <p>A |CallExpression| evaluation that executes step 6.a.vii is a <dfn>direct eval</dfn>.</p>
+        <p>A |CallExpression| evaluation that executes step 6.a.vi is a <dfn>direct eval</dfn>.</p>
         <emu-grammar>CallExpression : CallExpression Arguments</emu-grammar>
         <emu-alg>
           1. Let _ref_ be the result of evaluating |CallExpression|.
@@ -23417,17 +23416,17 @@ <h1>eval ( _x_ )</h1>
         1. Assert: The execution context stack has at least two elements.
         1. Let _callerContext_ be the second to top element of the execution context stack.
         1. Let _callerRealm_ be _callerContext_'s Realm.
-        1. Let _calleeRealm_ be the current Realm Record.
-        1. Perform ? HostEnsureCanCompileStrings(_callerRealm_, _calleeRealm_).
-        1. Return ? PerformEval(_x_, _calleeRealm_, *false*, *false*).
+        1. Return ? PerformEval(_x_, _callerRealm_, *false*, *false*).
       </emu-alg>
 
       <emu-clause id="sec-performeval" aoid="PerformEval">
-        <h1>Runtime Semantics: PerformEval ( _x_, _evalRealm_, _strictCaller_, _direct_ )</h1>
-        <p>The abstract operation PerformEval with arguments _x_, _evalRealm_, _strictCaller_, and _direct_ performs the following steps:</p>
+        <h1>Runtime Semantics: PerformEval ( _x_, _callerRealm_, _strictCaller_, _direct_ )</h1>
+        <p>The abstract operation PerformEval with arguments _x_, _callerRealm_, _strictCaller_, and _direct_ performs the following steps:</p>
         <emu-alg>
           1. Assert: If _direct_ is *false*, then _strictCaller_ is also *false*.
           1. If Type(_x_) is not String, return _x_.
+          1. Let _evalRealm_ be the current Realm Record.
+          1. Perform ? HostEnsureCanCompileStrings(_callerRealm_, _evalRealm_).
           1. Let _thisEnvRec_ be ! GetThisEnvironment().
           1. If _thisEnvRec_ is a function Environment Record, then
             1. Let _F_ be _thisEnvRec_.[[FunctionObject]].