Import v8 cpu profile (old format) (#177)

As said on #170, i added the support for the old format used by https://github.com/hyj1991/v8-profiler-node8 (which is currently used for pm2.io).

sample/programs/javascript/convertToOld.js

@@ -0,0 +1,60 @@
+/*
+* This script is used to reconstruct an cpu profile from chrome with an old format
+* still used in nodejs with v8-profiler
+*/
+const fs = require('fs')
+
+const data = JSON.parse(fs.readFileSync('../../profiles/Chrome/65/simple.cpuprofile').toString())
+
+const _convertTimeDeltas = (profile) => {
+  if (!profile.timeDeltas) return null
+  let lastTimeUsec = profile.startTime
+  const timestamps = new Array(profile.timeDeltas.length + 1)
+  for (let i = 0; i < profile.timeDeltas.length; ++i) {
+    timestamps[i] = lastTimeUsec
+    lastTimeUsec += profile.timeDeltas[i]
+  }
+  timestamps[profile.timeDeltas.length] = lastTimeUsec
+  return timestamps
+}
+
+const reformatNode = node => {
+  if (!node.children) node.children = []
+
+  node.children = node.children.map(childID => {
+    if (typeof childID !== 'number') return childID
+    const childNode = data.nodes.find(node => node.id === childID)
+    if (typeof childNode !== 'object') return null
+    childNode.callUID = node.id
+    return childNode
+  })
+  return {
+    functionName: node.callFrame.functionName,
+    url: node.callFrame.url,
+    lineNumber: node.callFrame.lineNumber,
+    callUID: node.callUID,
+    bailoutReason: '',
+    id: node.id,
+    scriptId: 0,
+    hitCount: node.hitCount,
+    children: node.children.map(reformatNode)
+  }
+}
+
+// reformat then only keep the root as top level node
+const nodes = data.nodes
+  .map(reformatNode)
+  .filter(node => node.functionName === '(root)')[0]
+
+// since it can be undefined, create an array so execution still works
+if (!data.timeDeltas) {
+  data.timeDeltas = []
+}
+
+fs.writeFileSync('./new.cpuprofile', JSON.stringify({
+  head: nodes,
+  startTime: Math.floor(data.startTime / 1000000),
+  endTime: Math.floor(data.endTime / 1000000),
+  samples: data.samples,
+  timestamps: _convertTimeDeltas(data)
+}))