cleans up sdk patching so we no longer have unresolved names

cleans up sdk patching so we no longer have unresolved names

js_codegen.dart and patch_sdk.dart are the only human-changed files.

This also pulls in dart:isolate, which is depended on from one of the implementation libraries

This also moves dart:_* files back to `lib/_internal/compiler/js_lib/` because there's where libraries.dart points to, and hence Analyzer looks for them there. Alternatively, we could put them somewhere like `tool/input_sdk_internal` and then copy that file into the right path.

R=vsm@google.com

Committed: https://github.com/dart-lang/dev_compiler/commit/d6195e020d36bbfb568a0a16ab62330ed5f57705

[Jennifer Messerly, 2015-02-26 00:10:08]

jmesserly@google.com changed reviewers:
+ vsm@google.com

[Jennifer Messerly, 2015-02-26 00:16:11]

FYI: this builds on the previous 2 CL's related to tool/patch_sdk ... this is
just showing the diff assuming those 2 are landed first

[vsm, 2015-02-26 16:54:50]

lgtm

[Jennifer Messerly, 2015-02-27 01:58:19]

Committed patchset #3 (id:20001) manually as
d6195e020d36bbfb568a0a16ab62330ed5f57705 (presubmit successful).