bindings: Use an alias for @@iterator in certain declarations.

third_party/WebKit/LayoutTests/external/wpt/fetch/api/headers/headers-idl-expected.txt

-This is a testharness.js-based test.
-PASS Headers interface: existence and properties of interface object 
-PASS Headers interface object length 
-PASS Headers interface object name 
-PASS Headers interface: existence and properties of interface prototype object 
-PASS Headers interface: existence and properties of interface prototype object's "constructor" property 
-PASS Headers interface: operation append(ByteString,ByteString) 
-PASS Headers interface: operation delete(ByteString) 
-PASS Headers interface: operation get(ByteString) 
-PASS Headers interface: operation has(ByteString) 
-PASS Headers interface: operation set(ByteString,ByteString) 
-FAIL Testing Symbol.iterator property of iterable interface Headers assert_equals: @@iterator function does not have the right name expected "entries" but got ""
-FAIL Testing pair iterable interface Headers assert_equals: entries method is not the same as @@iterator expected function "function entries() { [native code] }" but got function "function () { [native code] }"
-PASS Headers interface: operation entries() 
-PASS Headers interface: operation keys() 
-PASS Headers interface: operation values() 
-PASS Headers interface: operation forEach(function,any) 
-PASS Headers interface: new Headers() must inherit property "append" with the proper type (0) 
-PASS Headers interface: calling append(ByteString,ByteString) on new Headers() with too few arguments must throw TypeError 
-PASS Headers interface: new Headers() must inherit property "delete" with the proper type (1) 
-PASS Headers interface: calling delete(ByteString) on new Headers() with too few arguments must throw TypeError 
-PASS Headers interface: new Headers() must inherit property "get" with the proper type (2) 
-PASS Headers interface: calling get(ByteString) on new Headers() with too few arguments must throw TypeError 
-PASS Headers interface: new Headers() must inherit property "has" with the proper type (3) 
-PASS Headers interface: calling has(ByteString) on new Headers() with too few arguments must throw TypeError 
-PASS Headers interface: new Headers() must inherit property "set" with the proper type (4) 
-PASS Headers interface: calling set(ByteString,ByteString) on new Headers() with too few arguments must throw TypeError 
-PASS Headers interface: new Headers() must inherit property "entries" with the proper type (6) 
-PASS Headers interface: new Headers() must inherit property "keys" with the proper type (7) 
-PASS Headers interface: new Headers() must inherit property "values" with the proper type (8) 
-PASS Headers interface: new Headers() must inherit property "forEach" with the proper type (9) 
-PASS Headers interface: calling forEach(function,any) on new Headers() with too few arguments must throw TypeError 
-Harness: the test ran to completion.
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