Fix ddc USAGE doc.

pkg/dev_compiler/USAGE.md

 # Usage
 
-The [Dart Dev Compiler](README.md) (DDC) is an **experimental**
-development compiler from Dart to EcmaScript 6.  It is
-still incomplete, under heavy development, and not yet ready for
-production use.
+The [Dart Dev Compiler](README.md) (DDC) is an **experimental** development
+compiler from Dart to EcmaScript 6. It is still incomplete, under heavy
+development, and not yet ready for production use.
 
 With those caveats, we welcome feedback for those experimenting.
 
-The easiest way to compile and run DDC generated code for now is via NodeJS.  The following instructions are in a state of flux - please expect them to change.  If you find issues, please let us know.
+The easiest way to compile and run DDC generated code for now is via NodeJS.
+The following instructions are in a state of flux -- please expect them to
+change. If you find issues, please let us know.
 
-(1) Clone the [DDC repository](https://github.com/dart-lang/dev_compiler) and set the environment variable DDC_PATH to your checkout.
+1.  Clone the [DDC repository](https://github.com/dart-lang/sdk) and
+    set the environment variable `DDC_PATH` to the `pkg/dev_compiler`
+    subdirectory within wherever you check that out.
 
-(2) Install nodejs v6.0 or later and add it to your path.  It can be installed from:
+2.  Install nodejs v6.0 or later and add it to your path. It can be installed
+    from:
 
-https://nodejs.org/
+    https://nodejs.org/
 
-Note, v6 or later is required for harmony / ES6 support.
+    Note, v6 or later is required for harmony / ES6 support.
 
-(3) Create a node compatible version of the dart_sdk:
+3.  Define a node path (you can add other directories if you want to separate
+    things out):
 
-```
-dart $DDC_PATH/tool/build_sdk.dart --dart-sdk $DDC_PATH/gen/patched_sdk/ --modules node -o dart_sdk.js
-```
+    ```sh
+    export NODE_PATH=$DDC_PATH/lib/js/common:.
+    ```
 
-You can ignore any errors or warnings for now.
+4.  Compile a test file with a `main` entry point:
 
-(4) Define a node path (you can add other directories if you want to separate things out):
+    ```sh
+    dart $DDC_PATH/bin/dartdevc.dart --modules node -o hello.js hello.dart
+    ```
 
-```
-export NODE_PATH=.
-```
+    Note, the `hello.js` built here is not fully linked. It loads the SDK via a `require` call.
 
-(5) Compile a test file with a `main` entry point:
+5.  Run it via your node built in step 1:
 
-```
-dart  $DDC_PATH/bin/dartdevc.dart --modules node -o hello.js hello.dart
-```
+    ```sh
+    node -e 'require("hello").hello.main()'
+    ```
 
-Note, the `hello.js` built here is not fully linked.  It loads the SDK via a `require` call.
+6.  Compile multiple libraries using summaries. E.g., write a `world.dart` that
+    imports `hello.dart` with it's own `main`. Step 5 above generated a summary
+    (`hello.sum`) for `hello.dart`. Build world:
 
-(6) Run it via your node built in step 1:
+    ```sh
+    dart $DDC_PATH/bin/dartdevc.dart --modules node -s hello.sum -o world.js world.dart
+    ```
 
-```
-node -e 'require("hello").hello.main()'
-```
+    Run world just like hello above:
 
-(7) Compile multiple libraries using summaries.  E.g., write a `world.dart` that imports `hello.dart` with it's own `main`.  Step 5 above generated a summary (`hello.sum`) for `hello.dart`.  Build world:
+    ```sh
+    node -e 'require("world").world.main()'
+    ```
 
-```
-dart $DDC_PATH/bin/dartdevc.dart --modules node -s hello.sum -o world.js world.dart
-```
+7.  Node modules do not run directly on the browser or v8. You can use a tool
+    like `browserify` to build a linked javascript file that can:
 
-Run world just like hello above:
+    Install:
 
-```
-node -e 'require("world").world.main()'
-```
+    ```sh
+    sudo npm install -g browserify
+    ```
 
-(8) Node modules do not run directly on the browser or v8.  You can use a tool like `browserify` to build a linked javascript file that can:
+    and run, e.g.,:
 
-Install:
-```
-sudo npm install -g browserify
-```
+    ```sh
+    echo 'require("world").world.main()' | browserify -d - > world.dart.js
+    ```
 
-and run, e.g.,:
-```
-echo 'require("world").world.main()' | browserify -d - > world.dart.js
-```
-
-The produced `world.dart.js` fully links all dependencies (`dart_sdk`, `hello`, and `world`) and executes `world.main`.  It can be loaded via script tag and run in Chrome (stable or later).
+    The produced `world.dart.js` fully links all dependencies (`dart_sdk`,
+    `hello`, and `world`) and executes `world.main`.  It can be loaded via
+    script tag and run in Chrome (stable or later).
 
 ## Feedback
 
-Please file issues in our [GitHub issue tracker](https://github.com/dart-lang/sdk/issues).
+Please file issues in our [GitHub issue
+tracker](https://github.com/dart-lang/sdk/issues).
 
-You can also view or join our [mailing list](https://groups.google.com/a/dartlang.org/forum/#!forum/dev-compiler).
-
-
-
+You can also view or join our [mailing
+list](https://groups.google.com/a/dartlang.org/forum/#!forum/dev-compiler).