eslint: Add whitespace indentation configuration.

This should help prevent problems with folks introducing new code that
doesn't match our whitespace style.

There's a couple things I don't like about this configuration:

* How it handles multi-line JS lists (i.e. the [] syntax)
* That we ended up having to turn off indentation on a half-dozen
  files that apparently don't use our standard IIFE indentation style.
* That we have it completely turned off for the node tests; ideally,
  we'd just have slightly different rules around the IIFE identation story.

But otherwise, this works pretty well, and should catch a pretty wide
range of indentation regressions.

.eslintrc.json

@@ -208,6 +208,15 @@
         "eqeqeq": 2,
         "func-style": [ "off", "expression" ],
         "guard-for-in": 2,
+        "indent": ["error", 4, {
+            "ArrayExpression": "first",
+            "outerIIFEBody": 0,
+            "ObjectExpression": "first",
+            "SwitchCase": 0,
+            "CallExpression": {"arguments": "first"},
+            "FunctionExpression": {"parameters": "first"},
+            "FunctionDeclaration": {"parameters": "first"}
+        }],
         "keyword-spacing": [ "error",
             {
                 "before": true,

frontend_tests/.eslintrc.json

@@ -14,6 +14,7 @@
     },
     "rules": {
         "no-sync": 0,
+        "indent": 0,
         "prefer-const": "error"
     }
 }