[debugger] expose side-effect free evaluate to inspector.

src/inspector/js_protocol.json

 {
     "version": { "major": "1", "minor": "2" },
     "domains": [
     {
         "domain": "Schema",
         "description": "Provides information about the protocol schema.",
         "types": [
             {
                 "id": "Domain",
                 "type": "object",
@@ skipping 617 matching lines @@
             },
             {
                 "name": "evaluateOnCallFrame",
                 "parameters": [
                     { "name": "callFrameId", "$ref": "CallFrameId", "description": "Call frame identifier to evaluate on." },
                     { "name": "expression", "type": "string", "description": "Expression to evaluate." },
                     { "name": "objectGroup", "type": "string", "optional": true, "description": "String object group name to put result into (allows rapid releasing resulting object handles using <code>releaseObjectGroup</code>)." },
                     { "name": "includeCommandLineAPI", "type": "boolean", "optional": true, "description": "Specifies whether command line API should be available to the evaluated expression, defaults to false." },
                     { "name": "silent", "type": "boolean", "optional": true, "description": "In silent mode exceptions thrown during evaluation are not reported and do not pause execution. Overrides <code>setPauseOnException</code> state." },
                     { "name": "returnByValue", "type": "boolean", "optional": true, "description": "Whether the result is expected to be a JSON object that should be sent by value." },
-                    { "name": "generatePreview", "type": "boolean", "optional": true, "experimental": true, "description": "Whether preview should be generated for the result." }
+                    { "name": "generatePreview", "type": "boolean", "optional": true, "experimental": true, "description": "Whether preview should be generated for the result." },
+                    { "name": "throwOnSideEffect", "type": "boolean", "optional": true, "experimental": true, "description": "Whether to throw an exception if side effect cannot be ruled out during evaluation." }
                 ],
                 "returns": [
                     { "name": "result", "$ref": "Runtime.RemoteObject", "description": "Object wrapper for the evaluation result." },
                     { "name": "exceptionDetails", "$ref": "Runtime.ExceptionDetails", "optional": true, "description": "Exception details."}
                 ],
                 "description": "Evaluates expression on a given call frame."
             },
             {
                 "name": "setVariableValue",
                 "parameters": [
@@ skipping 346 matching lines @@
             {
                 "name": "heapStatsUpdate",
                 "description": "If heap objects tracking has been started then backend may send update for one or more fragments",
                 "parameters": [
                     { "name": "statsUpdate", "type": "array", "items": { "type": "integer" }, "description": "An array of triplets. Each triplet describes a fragment. The first integer is the fragment index, the second integer is a total count of objects for the fragment, the third integer is a total size of the objects for the fragment."}
                 ]
             }
         ]
     }]
 }