error in handling of "+" in presence of operator overloading

[dgrove]

@r1752:

> cat frog-test.dart
var i = "7";
var s = 9;
main() {
 print(i+s);
}

class foo {
 operator+(foo x) => (x + 1);
}

> ./frogsh frog-test.dart

node.js:134
        throw e; // process.nextTick error, or 'error' event on first tick
        ^
TypeError: Object 7 has no method '$add'
    at $add (evalmachine.<anonymous>:6:17)
    at main (evalmachine.<anonymous>:42:9)
    at evalmachine.<anonymous>:51:1
    at main (/Users/dgrove/repo/dart-bleeding/dart/frog/frogsh:22959:10)
    at Object.<anonymous> (/Users/dgrove/repo/dart-bleeding/dart/frog/frogsh:23295:1)

> ../xcodebuild/Release_ia32/dart frog-test.dart
79

[DartBot]

This comment was originally written by jimhug@google.com

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Set owner to jimhug@google.com.
Added Started label.

[DartBot]

This comment was originally written by jimhug@google.com

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http://codereview.chromium.org/8677018/

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Added Fixed label.